Greetings All:

First off let me say I am brand-spankin-new to Linux. I have only been using it for about a week now, so I will apologize in advance if the answers to some of my questions should be obvious.

I have an old computer that I am trying to set up as a OX server, maybe not the best first project, but hey it's cool stuff, and it is just for fun at this point.

Anyway I have installed Ubuntu 7.04 LAMP server (and then ubuntu-desktop on top) and run the Community Edition Installer. It seems to have worked b/c I can log in as the testuser from any machine on my local network. So now I think that I need to do three main tasks to really make it functional:

1) I created a sub domain say at my hosting company and pointed it to my home's external ip address using an A record. I will open port 80 to my server's local ip address. My question is what needs to be done on the server to finish that process so when I enter in a web browser on any computer (not local) I will see my login page?

2) I also created an MX record for and pointed at my ip address. What needs to be done on my server so when mail is sent to it will be delivered? I think I need to open port 25 and/or 143 to my server, but what else?

3) I need to delete testuser and create a real user. I think I know how to do this.

Thank you in advance for your help.