Need some advice plz

This is the 4th day of germination and the seed just sprouted out from rockwool but now the leaf of the plant hasnt seperated from each other yet, its got a yellow things cover it
What should i do? Any suggestion? Put it under lights or keep it in the dark?

no pic showing

if she has popped then put her under some cfl or t5, shouldnt be in the dark at this point. be sure not to cook her under a mh just yet. a pic always helps