Can't you find something like a guide or walktrough? I can't believe you're the first person using a RasPi as an access point...
I mean I would love to help. But it's a bit difficult without seeing the situation. And "I can't connect to anything" isn't exactly detailed enough to lead me to any conclusions. There are a lot of moving parts in a router, the wifi itself, DHCP, routing, firewall, ...