We have a lab who can't do the multiple steps for our fiver. I have made ramps, and also we've used a Pet Step folding ramp, shown at this link:
http://www.amazon.com/pet-supplies/dp/B00006OALWThat ramp is very sturdy and the dog has good confidence with it. But it is heavy and bulky. The ones I've made worked okay as long as they were wide enough, say at least 16", and covered with a carpet with thick enough pile to prevent slippage by the dog's feet. The angle is fairly steep on a ramp, so the footing really has to be secure. The actual ramp can be 1/2" plywood, and should be at least 54" long, which will probably be sitting on the second or third step off the ground. Our dog goes up the final step or two, above the ramp.
The plywood ramps are lighter and simpler than the folding Pet Step ramp, but make sure to router the edges or you will get slivers.
