Do you know what 'flatten the image' means? Read more here: http://wiki.gimp.org/gimp/
If still blur I suggest a trip to the next library for a basic guide into digital image editing. No point using a powerful tool without the basic knowledge.
u should really do some degree of research before asking here, even in this subforum. just a simple google search is faster than drafting ur question out and waiting for someone to reply.
just my 2 cents worth, sorry if i sound unfriendly and unhelpful.