Step by step instructions on an installation are going to be very difficult to obtain for your exact situation because there are so many unknown variables. However, I can provide some guidance to get you started and I’m sure everyone can them help out with more detailed specific questions as they arise. Here is a Microsoft article that may help, KB884453.
First and foremost some requirements to get exchange working properly:
- You’ll likely need a static address from your ISP. (STrongly recommended so you don’t have to mess with DNS constantly)
- You’ll need to setup the MX record for your domain to point to this address
- You’ll need to configure your firewall to forward TCP port 25 into your exchange server.
- Optionally, you’ll need to forward port 80 and 443 to your exchange server (or your Outlook Web Access (OWA) server, if they are different.)
- Likely, but probably not required, You’ll need to purchase or self issue a SSL certificate to use in your OWA configuration so you can view your e-mails in OWA via HTTPS (secure ssl).
Here are some likes that look like good articles as well.