Here is a pick of the tray with the lid on. See the mist all over the clear lid? Thats how you know you have enough moisture inside. Once your sprouts have come up good and strong, then remove the lid to get some air circulation around them to help prevent dampening off. I may even place a small fan on them during the day to strengthen them and get good air flow.
I almost forgot to mention a very important resource we all have available for free. Your county extension agency. I hopped over to mine, and was able to save to my computer, a gardening calender, that shows me when I should start things for my particular area, plus recommendations for when to do certain gardening chores. I saved mine to my desktop for quick reference. In fact it tells me I need to get on the ball with sowing my head lettuce, cauliflower, broccoli, and cabbage. Guess what i am going to be doing today?