1- رفتم: it is refer to past tense, for ex. I went to school. ( من به مدرسه رفتم) Although I think you must be know how to say past tens with different pronouns, I write it for you
I went to school ( من به مدرسه رفتم)
you went to school(تو به مدرسه رفتی)
he/she went to school(او به مدرسه رفت)
we went to school(ما به مدرسه رفتیم)
you went to school(شما به مدرسه رفتید)
they went to school (آنها به مدرسه رفتند)
2-رویم: It is refer to present tense , for ex. we go to school ( ما به مدرسه می رویم)
I go to school( من به مدرسه می روم)
you go to school(تو به مدرسه می روی)
he/she goes to school(او به مدرسه می رود)
we go to school(ما به مدرسه می رویم)
you go to school(شما به مدرسه می روید)
they go to school(آنها به مدرسه می روند)