In short, send a letter of intent to their majesties and kingdom seneschal before March 15.
Here are the basics of what you need to know, but make sure you look at the the full kingdom law, at the Drachenwald website.
7.02.2 Requirements for Participation:
7.02.2.1 Each competitor in the Crown Tournament must be fighting for a prospective consort of a different gender than his or her own. The competitor and prospective Consort are referred to as "Participants" in these laws.
7.02.2.2 Participants must be able to fulfill the duties of the Crown as outlined in 2.02.
7.02.2.3 Participants must be acceptable to the Crown and declare their intent to participate in a letter submitted to the Crown and Kingdom Seneschal 30 days prior to the date scheduled for Crown List. The Participants' letter of intent must include at least:
7.02.2.3.1 Proof of membership (as described by Governing Policy and Decision #4: Enforcement of membership requirements for participating in Crown and Coronet Lists).
7.02.2.3.2 Proof of current fighter authorization for the competitor.
7.02.2.3.3 The modern and SCA names of the Participants along with their address(es) and other contact information..
7.02.2.4 Participants must both be present at the Crown Tournament.
7.02.2.5 Participants must be at least eighteen years old on the day of the Tournament.
7.02.2.6 The Participants may not be Territorial Coronets, nor the Crown's appointed representatives of a Crown Principality (such as Viceroy and/or Vicereine), at the time of the Crown Lists or at any time during their tenure as successor or Drachenwald Crown.
7.02.2.7 Each person must be a member of the S.C.A., and must live at a residence with direct access to the Dragon's Tale. The Victor and Consort must maintain their membership without lapse, throughout Their tenure as Successors and Crowns.
7.02.2.8 The intent of a residency requirement is to ensure that participants in the Crown List are familiar with Drachenwald culture, traditions, and customs and that they understand the unique aspects of our Kingdom. Therefore the residency requirements for all participants are:
7.02.2.8.1 Participants must have resided in Drachenwald for the six months preceding the Crown List entered.
7.02.2.8.2 Each participant must have attended at least six official events (before Crown Tournament), held in Drachenwald, listed on the Kingdom Calendar in the Dragon's Tale, in the preceding twelve months. Additionally, each participant must have attended one official event (defined by the same requirements), more than 6 months before Crown Tournament but not more than 24 months before Crown Tournament. This event may be one of the six but does not need to be.
7.02.3 Each Participant will sign a statement, prior to the tourney, saying that they meet the requirements for membership (as stated in GPD#4) and other requirements as listed above.. This statement will be kept by the Seneschal's Office until the end of the Victor's reign.
2.00 CONCERNING THE DUTIES AND PRIVILEGES OF THE CROWN
2.01 The Crown shall consist of the Sovereign and Consort, as defined in Corpora. These two shall have equal powers and neither may act without the other, except as provided herein.
2.02 Duties of the Crown
2.02.1 Being present at Their Coronation, the next Crown Tournament, the Coronation of Their Successors, and such meetings of Curia as They hold during Their reign.
2.02.2 The Crown must be able to maintain rapid communication with one another, their Kingdom officers, and the population for the duration of their reign.
2.02.3 Being for Their people examples of chivalry, courtesy, and the virtues appropriate to noblemen and noblewomen, and encouraging these virtues in Their people.
2.02.4 Knowing, upholding and abiding by the Laws of the Kingdom, and the By-Laws and Corpora of the S.C.A. along with any duly enacted additions or amendments.
2.02.5 Being true and faithful servants of Their Realm: upholding Their people's rights, working for their benefit, maintaining the Crown's justice among all subjects in Their Kingdom.
2.02.6 It is the responsibility of the Crown to ensure that a list of all awards granted by Them is received by the Schwarzdrachen Herald and the Chronicler.
2.02.7 Watching over and encouraging the Arts and Sciences in the Kingdom.
2.02.8 Encouraging special care in the extension of hospitality and welcome to new and prospective members.
2.02.9 Maintaining files to be turned over to the Successors at such time as They ascend to the thrones.
2.02.10 Relinquishing any office held, for the duration of the Reign.
2.02.11 There shall exist certain regalia, which shall remain the property of the Kingdom, but shall be in the keeping of the Crown. The care and maintenance of this regalia shall be solely the responsibility of the Crown. The use of this regalia shall be solely the prerogative of the Crown. This regalia may include, but is not limited to: crowns, scepters, staves, weapons, shields, banners, cloaks, and robes.
2.03 Privileges of the Crown
2.03.1 The right to acknowledge the attainment of County or Duchy title by those who have met the requirements. In the event that either Monarch does not possess a Patent of Arms, two months before Coronation the Crown Prince and Princess shall poll all Patent-holding Royal Peers resident in Drachenwald. If, after the polling, the Crown Prince and Princess feel that the Monarch meets Corpora standards, then the Monarch shall receive a Patent of Arms upon descending the Throne.
2.03.2 The right to make and repeal such laws as the Crown shall deem necessary for the conduct of the Kingdom, subject to the laws of Drachenwald.
2.03.3 The right to receive such gifts as may be made to the Crown during Their Reign and to preserve such gifts for Their Successors. The right to receive such personal gifts as shall be made during Their Reign. The right to use such possessions and treasures during Their Reign as the Crown may already possess.
2.03.4 The sole right to call such Courts as may be necessary for the governance of the Kingdom.
2.03.5 The right of Sanctum. Sanctum shall be defined as the area ten feet in radius surrounding the Thrones and the Crown s presence, which may be used exclusively by the Crown and into which other members of the Kingdom may enter and/or share upon the invitation of the King and/or Queen.
2.03.6 The right to a clear direct line of sight between the King and/or Queen and the principal activity of the event.