What do I write in my answer?

You write the factual and legal defenses to the complaint. There are four ways you can answer a complaint they are:
 (1) An answer.
    An answer must include short and clear statements that either admit or deny specific allegations in a complaint, or state that the defendant does not have enough knowledge to admit or deny them. An answer must also state a factual and legal defenses of the party to the complaint. [ARCP 8(b),(c)]
(2) A motion to dismiss the complaint.
     A motion to dismiss on the following grounds may be made under this rule before an answer is filed: 
     (i)   A motion to dismiss for lack of jurisdiction (“jurisdiction” is the authority of the court over the subject matter of the lawsuit and over a defendant);
     (ii)  A motion to dismiss for improper venue (“venue” is the location of the court in which the lawsuit was filed);
     (iii)  A motion to dismiss for improper service of the summons and complaint;
     (iv) A motion to dismiss because the complaint does not state a valid claim, even if the facts alleged in the complaint are assumed to be true. [ARCP 12(b)]
(3) A motion for a more definite statement.
    This motion must allege that the complaint is unclear. A motion for a more definite statement must point out the defects that make the complaint unclear, and the types of details that should have been provided. [ARCP 12(e)]
(4) A motion to strike the complaint.
    This motion must allege that the complaint contains immaterial, impertinent, or scandalous allegations, and that it should be stricken partially or entirely. [ARCP 12(f)].
For more information you may want to consult an attorney.
Resources:
•    Rule 116 of Justice Court Rules of Civil Procedure
•    Rule 8 of Arizona Rules of Civil Procedure
•    Rule 12 of Arizona Rules of Civil Procedure