Ok so I just dyed my hair blonde and I hate it. Can I dye it back to brown with brown dye? Or will it turn red or something?

What kind of blonde is it? Ash or more golden?
My hair was ash blonde and I had to go to the hairdressers because she had to put red dye in then brown so it didn't look dull.
If your hairs golden blonde then a neutral brown would probably look OK.

=]

Its more of a brassy or redish blonde

In that case I would get a perminant nice 'n' easy light ash brown or medium brown depending on what you want and use that. It will get rid of the brassiness and leave a natural brown colour.

=]