Check your local hydroponic store for a tray and a plastic dome to cover your seedlings. This will keep the humidity in. Hydro Farm sells a nice 2' grow lite which will fit nicely over the dome. Oh,yeah. The heat pad goes under the tray.
Bob

Ruthann,
I have tried it both ways. Trying to root cuttings, I put the pots on a low, cake cooling rack about 3/4" over the heating pad. The cuttings seemed to progress very slowly, if at all. I then put the pots directly on the pad and the cuttings rooted pretty quickly. With seedlings, it seemed to be too hot directly on the pad and the soil dried out very quickly. I bought some metal screening with about 1/2" squares and folded it in two and placed that on the pad. This raised the pots about 1/4 to 1/2" over the pad. The pots still got warmed and the soil stayed slightly moist longer.

The dome suggestion is a good one. It will also prevent the soil from drying too quickly. I built a tent over the seedlings using some stakes and transparent plastic tarp. I had them in a growhouse so I didn't have to worry about wind knocking it on top of the seedlings and rooting seeds.
Mike

Thanks for suggestions Bob and Mike. Now I have enough info to make me dangerous...lol. Sincerely, Thanks! I had no clue as to how to start with a heating pad. ruthann

I bought a seed mat to root cuttings over the winter. I put the cuttings in plastic water bottles and put 3 bottles in each black pot. I placed the pots on the seed mat and covered it with a simple greenhouse type cover that I made with dowel rods and clear plastic(painting tarp). I kept it in the house by the window. It worked very well for me. The seed mat was an inexpensive one that I got on ebay. No thermostat or controls. Just plug it in and put the pots on it.
Vivian