OK if you want to put a border around an image in photoshop 7:

Select the image / part of the image that you want to put a border around.

Click the Select or Selection menu.

Click Modify and choose border

Decide how wide you want the border, type it in and click ok

Set the colour you want for the border as the forground colour

Click paintbrush or pencil and choose a suitable brush or pencil

Paint/pencil all over the border selection. Your painting can go outside the border selection, it won't show. Don't let there be any gaps

De/unselect everything when you're done.