It is mostly possible to upgrade your graphics card, but type depends on the motherboard. Which means if you are not terrible familiar with computers, it might be a daunting, if not impossible task.
So if you know somebody real life with a little computer knowledge, you could get them to look at your computer/manual for motherboard and perhaps give some recommendations.
(Oh, and please edit a post, when adding new/more information, instead of posting two times shortly after each other, especially when nobody has replied between that time

)