I started to learn Japanese really recently but I'm pretty sure it's "watashi ha gakusei desu" (わたしはがくせいです), the "ha" is pronunced "wa" by the way. It depend of the context though, like if you're already talking about yourself (for instance: if you're introducing yourself) then you don't have to put the "watashi ha" part though.

はじめまして。私はがくせいです。よろしくおねがいします。