Conjugation of Russian verbs is probably one of the trickiest things in Russian language. Eventually, with a lot of practice, you'll be using right forms automatically, but for now I recommend these websites:
If you can't find there the verb you need, try a similar verb (with similar suffixes and ending). You can search Wikitionary (Викисловарь) where you might find not only conjugations, but also synonyms, examples of usage and other things.
Do you know any other useful conjugators? Leave a comment below.