If you're sure he's gay, you might just lay it all out and ask for advice.
Otherwise, suggest a perfectly normal platonic activity you both might enjoy.
The trick is, honestly, to just be there to enjoy yourself, and make friends who may be suitable for other things as well… Don't try to "make up for lost time", or "catch up on being gay"… Just start opening the real you up a bit more until you're fully comfortable in your new "out" skin, and make a habit of meeting people, inviting them out, and just letting your new life happen.
After a while, some natural patterns/best practices for dealing with crushes may emerge, but for now just try not to get trapped too much by goals and expectations, they have a bad habit of putting a weird tinge on relationships of all kinds.
As a newly "out" gay guy, how do I tell another guy that I have a crush on him, without sounding creepy or pathetic?