Ok! A very basic mask lol.

I made this one in PSP7.

Open new transparent image 400 x 400.

Flood fill black.

Take your selection tool (round, rectangle etc).

Use the following settings;

shape = round, rectangle, ellipse whichever you wish to use

feather = 15

anti alias ticked

Draw shape on your image. Try to leave an equal margin all the way around and centre your image.

If you know how to use the ruler tool use it! (If not go to view, rulers. The rulers will show on your image.

Click on 50mm and holding down left mouse button draw your selection out to 350mm and release).

Flood fill white and de-select.

Layers, merge all (flatten)

Save as j-peg.

You have just made your first mask woopee!

This is what it should look like...ish :-)