propergater

There should be a mat in the base, and a funnel built into the side. Place your seed trays inside and water through the funnel to keep the mat damp. The vents on the lid should be closed until the seeds germinate, then open them for a little ventilation.

Is that enough to help you?

I use sand in the base of mine. It is too simple to have even a funnel and I remove the cover to water!

one has the mat the other i put a layer of compost in. water from a can. one has a thermostat control the other doesnt.
put a termometer inside when it is on and see what temperature it gets to. the one with the termostat i had to check at each setting to find out what it was doing.

Yes, I do have to remove the lid. It is not a posh one with a thermostat - it was second hand, so I can't complain! It is great to have it at all.