Can someone please help me with my advanced Spanish Homework?

Im in a college advanced spanish class and we are going over all the tenses. Now were on the Preterito tense and I am so lost, The teacher can not explain it to me like I need it to be. She wont even give me an example on how to do it. Okay well here are the directions. Poner en preterito 1. llueve, 2. repito. I don't get how you put that in the preterit tense because it doesn't end with an er, ar, or an ir so how do i do it? I have 27 of these to do total I just need to understand how to do it please :)