Growing Bonsai from seeds

Hello,
I have been growing bonsai from seeds and at this point I don't know what to do. They are very big and I don't know if I should repot them and how I should water them, sadly my other bonsai died... now I have the bonsai seedlings and I am stuck with what I should do.
Thanks!!!

These tiny seedlings should be outside in full sun. Make a transition slowly (From a living room into full sun will be a guarantee to disaster) Ideally planted in a growing bed for a few years, so the plant can get some wood on it.

Pines in general like to be on the dry side (But, as will almost all plants, should never completely dry out)

The critical thing is definitely full sun!