Most people are natted behind a router whether you have a static or dynamic ip address from your internet provider, I.E. your pc is plugged into the router/hub which in turn is plugged into your cable modem or DSL modem, etc.
If this is the case, you have two choices. Most routers allow you to specify which inside host is on a DMZ. You normally assign your pc a static private address from the router admin menu, such as 192.168.0.10 and then you tell the router that 192.168.0.10 is on the dmz. By doing this, when some goes to:
http://yourstatic_IP_ADDR , your router will re-route all the packets to your server/pc on the inside network, your home network.
This does expose your pc directly to the internet so you are forwarned.
A second method that can be used is port forwarding. You use this method normally if you are needing to open a few ports (21,22,25,80) and you tell your router to redirect packets sent to yourstatic_IP_ADDR port 80 to 192.168.0.10. port 80.
This exposes your PC less but every new port that you want to share to the outside world will need a port forward addition in the router.
Good luck.
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