At this point all you can do is wait for warmer temperatures around 60 F and then give your lawn more nitrogen fertilizer. You could also spread lime if you did not lime in the fall. Generally look for lawn fertilizer that is high in nitrogen that says something like covers 5,000 square feet. Calculate how many square feet your lawn is and spread the bag contents accordingly. Late March into April is another good time to seed so get seed similar to what you spread before and cover the bare spots. Throw a little compost or even straw over the seed to keep it moist for better germination. Seed needs to stay moist and not dry out during the 7-10 days it takes to germinate and start rooting. Once the grass has established for a month you can use a little herbicide to clean up weeds. Or you can spray the weeds now when it is dry and seed in April.