I'm assuming this is your configuration and what you mean by inside and outside is within the network and outside the network.
Server ---- router ---- internet
within the network you're in it's easy to access the server all you have to do is know the address assigned to your server by the router.
if you're attempting to access it outside the network (through the internet) you have to know a few things and have a few things set up. first you have to know the address assigned to you by your ISP. you can get a dyndns service that'll give you a domain name. some routers support this. in addition to knowing the ip you have to assign the router to forward traffic for a given port to a certain machine. for example if you're going to SSH into your computer (port 22) from outside the network, you need to have port 22 forwarded and pointing to the box with the SSHd server.
hopefully that clarifies some, if it's totally wrong (with the assumptions of internal and external) disregard this. btw, if you were more specific about stuff it'd be easier to diagnosis.
