Drop down menu

[dEnA]

Hi, I have done a car gallery (www.motorfreaks.org/gallery) for finnish tuning cars.
But if it ever gets popular I need to be able to sort the cars by brand.
So how can I do a drop down menu so that everyone can choose their cars brand and then in search you could search just for a particular brand. Sorry for my bad english, hope you can help me

EDIT: Forgot that I have this problem that I want to sort theese thumbnails by username alphabetially and not like this: http://motorfreaks.org/gallery/index.php?cat=1

EDIT2: And then this other thing I was wondering. How can I do so that everyone can watch eachothers profile. Or whats the idea in it otherwise?
thanks
"dEnA"

[Stramm]

use keywords to add the car's brand when you upload the pics
then have a look at the search.. you can search by keywords and there's alrteady a 'clickable keywords' search. If you want that in a dropdown... have a look at include/keyword.inc.php the parts you'll have to modify are mainly html