I found several ideas for you- good luck and post photos of your finished projects.
This site has 15 different ideas and some are adorable.
Here is another idea for you
The biggest thing I can recommend is to make sure you amend your soil for cactus and that it is well draining.
What zone are you in Kathy?
See if these sites help you out.
Cactus need well draining soil, so amend the area heavily and be sure it drains properly.