Yes, you may write your own petitions. Your priest or deacon can help you.
In the general intercessions, or prayer of the faithful, the Church intercedes for all of humanity. The following petitions are required:
For the needs of the Church
For public authorities and the salvation of the world
For those oppressed by any need
For the local community
The wedding ceremony may include prayers particular to the vocation of marriage and particular to the couple being married