pre-emergent weed and feed with some fertilizer.
Has the grass started to turn green yet? and what kind of grass?
If the grass is not green yet you can spray what weeds are there with roundup, it won't kill anything that is not green when it is sprayed. then use the pre-emergent to keep the new weeds down.
Depending on the grass variety it may fill in bald spots with proper water & fertilizing but if it is something like fescue then you'll need to reseed the spots.