Yup, its not working the way it should. Or am i doing it wrong?
Please help me by telling me how to properly resize in the Gimp.
I do not want to go to paint 'cause the quality goes, BOOM!
So please help.

Image > Image size

Thanks niall. very helpfull.

Quote from Dalek0220 :

Thanks niall. very helpfull.

You could at least tell what is exactly going wrong. With that info, the previous answer is the best you'll get.

I'm not sure if his answer was honest or sarcastic

It was honest. I found Image>>Scale Image. Just what i needed to change the size.

Lol, this is funny. You say it's not working properly... So I'd figure you know how to do it, just something wrong happens... But apparantly you didn't even know how to do it.
Then you ask: "how do I rescale an image in gimp?"

I'm baffled