Brakes locking up could be that the emergency brake safety cable was pulled out.

More likely, though, you added new fluid to a system that was full of rust/gunk and the cylinders just jammed. You also need to bleed the lines if they were completely empty. I'd just get some new wheel cylinders (they are cheap -- $25/each through eTrailer.com) and then I'd bleed quite a bit of fluid through them to try and flush out the gunky lines. Get speed bleeders -- they make this whole process really, really easy.