I am very new to Cisco firewalls(got kinda thrown into it) and I had a request come down the pipe to deny access to the internet for a single internal IP address. My firewall is a PIX 515e. I'm guessing it has to do with the access-list but I don't know if I need to create a group and add that one IP to it or really, even how to go about it. Any help would be appreciated.
From what you have posted it is difficult to find how the various access lists are applied (how they are being used). But it does seem that you will need another access list. What you want might look something like this:
access-list inside_access_out deny ip host any
access-list inside_access_out permit ip any any
access-group inside_access_out in interface inside