I was able to find a couple risers at an old construction site plus a friend had a couple so they didn't cost me anything. The 2x8s were treated lumber and more expensive than regular 2x8s. I got 10, 8foot long ones and that cost me about $45.00 plus a box of deck screws (galvanized)and some water sealant it ended up costing me in the neighborhood of about $75.00 total.
I put the risers up two on each side of the fence then put the 2x8s on. I cut the 45 deg angles on the steps and placed them on the risers before I cut the ends off. This way I was sure that they would be even and all I had to do was take my circle saw and trim them once I got done. I used deck screws to fasten the whole thing together as they are easy to use and if you have to take the project down they are easy to remove as well. Now everything's in place to start planting. I would advise though that you treat the lumber, risers and all, with a good water seal to protect against water damage because it will see a lot more water than what mother nature provides.
Now what do I grow?
I already had some house plants to start with so I used them to decorate the risers. I'd wanted to make this more than just a flower garden, I wanted to produce something useful but you have to be careful, just like anything else living your plants grow and take up more and more space, what may seem sparse in the spring could over grow themselves by August if your not careful, so don't let your enthusiasm overload you.
I stared out with some peppers, Jalapeno, Habanero, Cayenne etc etc. I've grown about five different varieties at one time. Of course these plants are seasonal and you have to replenish them every year so I decided to try some herbs as well, these are perennial and will come back each year. Thyme, Oregano, Basil are good ones because they are hardy and easy to grow. As you can tell I added some decorative plants and flowers to fill in but this was what it looked like in 2006. I've since gravitated to more eatable plants. Mose roses, or Portulaca is a good flowering plant to have, it has beautiful colors and is very hardy. Coleus is a good one for color also. I'll get more into the particular plants next installment. I hope this has given you some helpful ideas, gardening is fun so go on get your hands dirty.
