Your not being dumb at all! Yes you can buy stands for them, all sorts of different ones. Some will just take one gridwall and are basically a pair of legs. they are fairly stable. Or you can get triangle base to put three gridwalls together. Or you can longer ones to make a wall of gridwall with an end going the other way on each end, called a gondala (if that makes any sense)
However I have found through trial and expensive error that if you are putting more than two gridwalls together they will free stand. You need joining clips (which are quite cheap) and then just join them together, the triangle shape is very stable. Or you can do a gondala. I then just use tent pegs around the bottom on both sides so if winds do blow they will wobble but not go straight over. In very windy conditions you can add guy ropes as well.
Or... the other thing I do more often then the above is hang them straight of the frame of my stall. However they are fairly heavy so you can only do this if your frame is very strong. Mine is a market stall so is fine for this. I then use big metal S hooks to hang them. Occassionaly extra market clips to secure in the middle to stop them moving.
Anyway hope this helps, have a look at this site for ideas of how bases, joining clips work, it might be clearer! www.uni-shopfitting.com
and go to online shop and look under gridwall.