Hi kero_99, first of all, being 10yrs old is not a problem its great, it means you have lots of time to learn lots of really geeky things about your laptop and computing in general :-)
Firstly, we need to know the make (sony,hp,dell etc ) and model number of your laptop.
Secondly, we need to know what you are doing on your laptop when this gfxui error occurs; are you playing a game or are you on the internet, or just using the laptop for something else ( listening to music, watching a video etc )?
Thirdly, if you can, write down the error message; if at all possible and include this in your next post.
Get your mum or dad to help you with gathering all of this information so your next post will be complete, THEN we will see if we can help you resolve your problem.
Don't worry to much, most things can be solved with a little bit of thought and some searching on the internet, at places like Toms Hardware forums :-).
I shall check back daily to see if you have updated this post.
Good luck with the information gathering and i look forward to your next post :-)