Hea peeps, I am a noob when it comes to web design and I'v been trying to figure out how the websites like 99design and the likes work. Are they just a picture gallery or is it alot more complicated then that?
I'd say they're more complicated than that. Sites that let you post stuff, comment on things, and the like usually always run on some kind of database system with some sort of programming involved. There's a lot of stuff available that's pre-made so all you have to do is install and setup, but big sites like that usually involve some custom programming.
When I buy stickers for folks in prison, I bring milk not backyard meth - it's a prison party!
If your interested in building something along those scales then you need knowledge of database development and server side programming. One of the more popular server side programming languages is PHP. However, other languages such as ASP, Ruby, Python and Java can also be used given the correct server set-up. As far as databases go the more popular of them all is the open source version of MySQL. Databases are used to store the data. Server side languages are used to manipulate data and display it alongside HTML. Those are the two most work horses behind most dynamic web applications – a database and domain level programming "framework". A site like that would never be possible with only HTML and CSS.
Are you interested in the programming, design or both? Building a site like that requires a lot of programming outside what any software package can provide. Not to discourage you or anything, but its more less computer science then visual design.