First fill up the fluid, pump a bit and see what hapens. Check fluid level and look for leaks.
Break hoses, wheel cylinders are typical leak spots, also rusty lines, or your master cylinder is shot if you loose fluid.
If it don`t leaks and you have some presure at the pedal drive CAREFULLY to a shop that bleeds your breaks.
If it leaks, DON`T DRIVE AT ALL!!!
Ask an old hand to show you how to replace the shot parts.
Live and learn form an oldtimer is the best you can do.
Frank
