Steaming in the Halogen Oven

I fancy trying some steamed fish and vegetables in my oven but was wondering about the water. How much do I use and is there a risk that the steam generated could get into the lid and damage the electrics? Sorry if this is an idiot question but I would rather show my ignorance than ruin my oven.
I haven't got a steamer tray but was thinking of using foil parcels or putting the fish on the rack.

I really don't know what others do when steaming, I steam my veggies and often fish too, I simply make foil parcels or use the steamer tray and cover the lot with foil, probably have an inch of water I haven't had a disaster yet, having said that you can bet I'm gonna have one soon lol.

Regards Caz