need help with masking

ok what i was doing to some of my family pics was this.... it would be a picture of my parents... so what i did was mask it but to black. so instead of having the whole pic, most of the pic is faded black and the center is normal having my parents there... i did that fine. and now today i go use ps version 7 (same one i been using) and i go do that with my sister and her husband and when i try it wont let me go to layer... reveal all... its not highlighted it won't let me go... i also noticed that the pic is locked if i took it with my digital cam?...why is it locked? how do i unlock it? so to get around the lock what i did was made a another layer of the background so now the background is locked and the new layer i made isnt... i delete the background and now all i have is that new layer which is unlocked. then i go and do the layer reveal all and when i go try to blend some black in instead of blending black in. it blends the white and grey checkerd boxes as if i am masking with a new background. wtf? can someone please help me?

thanks in advance... some quick replies would be great. doing a slide show for my family tomorrow at a bbq... and i need to figure this out.