since ev nova is a 2d game tat uses mostly 2d models, i wanted to learn how to do some. Can anyone tell me which program is good for things like this. Is photoshop enough?
Nova ships are, as far as I know, exclusively 3d models. The 3d program then renders them into 2d sprites. It's possible to generate 2d models to use in Nova, and I believe a lot of the weapon sprites were, but your premise is quite flawed. If you want to make Nova-style graphics, you'll want to learn 3d, not 2d.
As for getting started with modeling, there's a stickied topic on "all the important links you'll ever need." It should help point you in the right direction.