They need bright, bright light. I would recommend turning he lid an inch to ventalate it as well.

As soon as you see sprout you have to provide bright lights immediately otherwise the seedlings will grow leggy and weak and later fall down.

I am doing the same thing you are and growing tomtoes and peppers. If the tomatoes are some what yellow thats a sign of to much water same with the peppers. If they are at least 1" high I think it is time to remove your lid and get some light on them. Some people may wait for the second leaf. But everyones conditions are different. I am using a florescent light on top of mine as close as I can get it about 8" closer is better. Its one of those like in a factory, round with a magnifing glass in it. I have got it clamped to an art table and it is on 2hrs off 1 24/7(timer) . If it is cold where you are you can leave the heating pad. My peppers are about 2" and have been un-covered for a least 2weeks. Same for the tomatoes. Hope this helps