your seedlings are looking great, cotyledens are out, and first bladed leaves are forming. And like smokingbot said, a little bit stretched. This is due to the fact you are using such a low output light. 1100 lumens is a little low, you should be running with at least 2500/SQ foot, 5000 is average, and 7500 will give the fastest growth possible. now you are gonna use a 600 W HPS, that is one of the best lights to use. 600 W HPS put's out 55,000 lumens, enough for up to 10 plants. This light should be kept about 2 feet away from the plants (24 inches), using how the plants react as your guide. If they start looking burnt, raise the light, and if they streatch a little bit, it can be lowered. just make sure the plants never touch the lights.