I've been having some issues with my mac computer?

I bought a computer through Sears. It came with Chinese as the main language, and I had to figure everything out myself. Word is useless because you can't change the main language that it came in, so I'm stuck using Open Office. When I try to update things in the app store, it won't let me because it says that I have another account hooked up to it (which I don't). What should I do?