Want to do~ ~たい

First get the ~ます masu form of the verb you want to do.  Then drop the ~ます masu and add ~たい tai

たべます tabemasu (to eat) Arrow image たべ tabe Arrow image たべたい tabetai (want to eat)
のみます nomimasu (to drink) Arrow image のみ nomi Arrow image のみたい nomitai (want to dri