DNS Help

First, I have searched google and nothing has really helped me.

I'm currently using BIND DNS and I have 2 websites behind a router from one public IP address. I'm trying to figure out how to get the dns to point to the correct server when someone types in the domain name. I have port 53(UDP) open on the router, don't know if anything else needs to be open.

The DNS server is setup on a linux box running ISPConfig 3 and I have messed around with the dns settings a lot to no success. Both domains go to one server. I have configured both domains to point to my DNS server through 1&1(not sure if correct). I ONLY have 1 dns server and 1 IP address. The ports are setup so that both servers are open on 80 and their other necessary ports for their services.

Server Setup:
Server one- Website and Minecraft server
Server two- Website and Mail server

If you need any more info I'll be happy to provide more info if need be. I know it seems kinda vague. Thanks in advance for your help!

Are you using a routing table?

No. If I knew how to set it up I would. I somewhat have good understanding of RIP but would you setup the route to go to the dns server first?