with questions like those, you'll get a million answers.
i'd tell you to junk the walmart bike and find something that won't fall apart, while other's will tell you to buid a 200cc 4 stroke.
your best bet is to grab something to drink, find a comfortable chair, and start reading older posts.
everything you want to know has already been asked, mostly solved, and is all right here in this forum.
use the search feature with your specific bike, and it'll probably turn up a few hundred posts you can sift through.
if you've got specific questions, ask away.
have fun with it...