Argentine Spanish? Command form in Vos?

I used to live in Argentina and so I've learned to use vos instead of tu. I've learned mostly from listening to conversations and others speaking, but I was curious as to the rules of how to conjugate command forms in vos? For example I remember the command for "come" (as in "you come here") to be "ven�" but I can't justify as to why or how.....? Word Reference doesn't cover vos conjugation. Can a native Argentina help me?