I bought some blood psd files but every time I load the in my Photoshop CS they are black and not red. Is it me or the files?

Difficult to say without seeing the files but they're probably meant to be like that so you can use your own colour - that way, they can be used for splatters of things other than blood. Just use a hue/saturation adjustment layer with 'colorize' checked.

Sadly using the hue/saturation on colorize didn't work for me. I thinking that maybe CS won't work for them.

 i'm not sure what your files are...

Are the psd files meant to be used as brushes? are they actual photographs of blood? or are they spatter drops that can be used as blood in a drawing?

check and see what your color mode is in your document when you open them.

odd that hue/saturation didn't work, i use it all the time...

retrocity

If it's completely black, hue and saturation won't work unless you lighten it before to turn it grey and then go to hue and saturation to colorize it. 

I'm thinking what you got are psd or png that are meant to be turned into brushes?  Once they are turned into brushes, you can use whatever color you want with them...  Or you can use the psd/png on their own layer, then go to Layer style/color overlay and pick your red.

it did say that they chould be turned into bushes, but there was no read me file to show me how to do that. Can I get a breif instruction on that?

It's really simple, open the document, select all, then go to edit/define brush preset , name it whatever you like and you should have this new brush in your brush palette.  To make sure you won't have to redo this every time you want to use them, once you've done this with all your psd's, go to edit/preset manager (in brushes), select all the brushes you've just created (do this by holding the ctrl key and clicking on all your brushes) and then click on save set calling it "blood splatters" or whatever you like...  ;)

One last thing, how do you change the color of a brush?

That's the foreground color at the bottom of your tool library, click on that little square and you can pick your color.