I am new to the bird thing can you please help!?

I just purchased a cage at walmart the other day and bought 2 birds its a smaller cage of course so please consider this during your answer. Im wondering if I am feeding a parakeet meal from walmart is that okay with the animal I never see it eat but its being really shy at this point until it gets comfortable im sure. Im looking to stimulate both animals as well as make sure beaks and everything else are taken care of I need advice I know nothing about birds as I have not kept them at all in my life except when we were younger and I dont remember to much about them then. Im more of a fish expert any help will be greatly appreciated and please do not go off on a rant at me thank you so much in advance!