Question

Translate into Tu form
Study hard
do your homework
be prepared
attend class on time

dont sleep in class
dont eat in class
dont talk in class
dont arrive late
dont use your phone in class

Answer 1

The first set is positive "tú" commands. Here's how you'd conjugate them:
-ar verbs: Drop -ar ending and add "a."
(Ex.: Habla español. = Speak Spanish.)
-er verbs: Drop -er ending and add "e."
(Ex.: Come la comida. = Eat the food.)
-ir verbs: Drop -ir ending and add "e.:
(Ex.: Escribe los apuntes. = Write the notes.)

*Also know the irregulars: http://www.studyspanish.com/lessons/irregtucomm.htm

The next set is negative "tú" commands. Here's how you'd conjugate them:
-ar verbs: Drop -ar, use opposite ending in tú form.
(Ex.: No hables español. = Don't speak Spanish.)
-er verbs: Drop -er, use opposite ending in tú form.
(Ex.: No comas la comida. = Don't eat the food.)
-ir verbs: Drop -ir, use opposite ending in tú form.
(Ex.: No escribas los apuntes. Don't write the notes.)

VERY helpful resource: http://www.studyspanish.com/verbs/lessons/informcomm.htm

Hope that helps! :)

Answer 2

I'll do the first ones of each set to show you:

Study hard. => Estudia mucho!

Don't sleep in class. => No duermas en la clase!

**I forgot: remember to stem change in positive and negative tú commands!!!