I have blender 2.63.
I have downloaded Antropus skin alphas.
Where do I put them in Debian to use them in sculpting texturing?
Not sure about 2.63, but you may put the textures wherever you want. Then in Blender, you create your brushes (in the Texture Panel) by opening the texture files.
I am in sculpting mode. My model is selected. I have opened my textures in file/open/images. They are named, for example : SKIN_pores.jpg. Blenders says “File format not supported etc.” Am I opening the file in the right place?
No 
http://cgcookie.com/blender/2013/07/10/using-brush-textures-for-painting-and-sculpting/
EDIT: I should probably note that some of the techniques and settings demonstrated in that video are not applicable to 2.63, with it being older.
Antropus skin alphas
SKIN_pores.jpg
jpegs do not have alpha chanel, it might be irrelevant here if that is just a b/w image.
Edit: To make it easier you could use this addon:
They’re just called “alphas”, eppo They’re really just greyscale images.
That reference was exactly what I needed. Not only did it answer all my questions, but it also taught me a lot of great things.
Unfortunately, it also raised a question. Why don’t I have a topology tab in my 3d view sculpt mode tools with the enable dynamic topology check box?
Because you are using blender 2.63. You need to be using blender 2.66 or later http://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.66/Dynamic_Topology_Sculpting
Ok. Thanks for your patience.
@Stan Pancakes: 
figured that one already; what a terrible confusion, such “simply calling”…
@S. Chapelin: hopefully addon will work on 2.63. It is certainly worth to upgrade to current Blender and check Dyntopo in action.
Well, not really a confusion. It’s a “brush alpha”. That is, an alpha (mask) for a brush.
It’s a reel NextGen confusion then - jpg called “alpha” which is b/w image which is creating alpha for a brush which in essence is an image…:eek:
Btw, is there any checkbox or keystroke “Invert” around for such an alpha? Couldn’t find at once but might come handy…
You’re overthinking this 
“Alpha”, by itself, be it in image or, in this case, brush intensity, is just a value from 0 to 1, right? Consider viewing just an alpha channel of an image. You’ll see greyscale image. So there, “alphas”
Btw, is there any checkbox or keystroke “Invert” around for such an alpha? Couldn’t find at once but might come handy…
No, you’d have to invert it beforehand in some image editing program.
I should probably also note that brushes in Blender are round, thus only the incircle of an image is being sampled when sculpting. So if you want to make some squares, you’d need to account for that when creating the alpha.
Back to square 1: b/w (grayscale) image = brush, no alpha;). Anyhow, thanks and apologies to OP for spamming .
No, you’d have to invert it
- kinda sad, mildly put.