Green leaves are greens, not browns. Drying them will only make them look brown - they are still green. Do not bother drying them - they'll compost faster when wet (they'll never compost if completely dry).

Are the brown ones that came down (in April?) from a dead tree? Then they are brown; normally the naturally shed leaves are browns.

If you need browns you can use sawdust (not pressure treated) or straw or even shredded newspaper.

Heck, no! If you can rake 'em, compost 'em! Water and a nitrogen source, micorhizzae and bacteria are necessary for composting. Wet leaves (carbon) and green leaves (carbon with a bit of nitrogen) are a start. The other two are generally available and will find your "pile" in nature. Go for it!
hortster