Salad stuff

So, Ive started off some seeds (and forgotten to label them - doh!), I think what's coming up first are the lettuces..I've no greenhouse so Ive put them into those seed trays with the lids on. Is this ok and what would be the next step please experts?
If I plant the young ones in the garden how can I grow them on organically?

 

I would take the lid off during the day and perhaps put it on at night although now, June, there is probably no need. Plant them out when they are big enough to handle and water well [once a day]until they are up and running and then add water if necessary preferably from a water butt.

 

Thanks hans, Ive kept the lids on as theyre outside, and didnt know if they'd get aphids or other things munching them