Use the magic wand tool (and adjust the tolerance setting) to get rid of the white fill and background. (if that's all a one-layer image). Then CTL+Click on the "seven" layer thumbnail in the layers palette to select the "seven" outline. Then go to Modify>Select>Expand and choose a pixel value. You can set your foreground color to black or a darker color, then hit ALT+BKSPC to fill. If you want the interior of the number colored, you can paint in black, or if you want a different color, create a new layer underneath it, and paint in another color, then merge the layers.
Depending on how you made the "7".
You can try messing with the blending options - you access it by right clicking on your layer in the layer panel (don't click on the thumnail but the text) and there you'll find Blending Options.
In blending options you'll find a lots of ways that you can add effect to our layer:
- You can add a stroke to your layer to make it more visible
- or your can use the bevel & emboss options and play around with that
@rbcc - You have already been given a couple of methods to enhance the number (ie, in posts #6 and 7) without using the pen or any similar tool. Have you tried these, particularly, the method described in post #6. If you haven't, you should. If you have and ran into problems, show us what happened.