You need a lot more than just the IP address.

1. In order to access anything on a computer, you need a file server of some kind--FTP, http, etc.

2. In order to make a file server work, you need two addresses--that of the computer itself, and that of the router to which said computer is connected.

2.1. To get the address of the computer on which the server is running, do the following:

2.1.1. Open the Windows Start menu by tapping the Windows Key.

2.1.2. In the search field, type cmd. Hear Windows say "Command prompt ..." etc. Press ENTER.

2.1.3. At the prompt, type "ipconfig" and press ENTER.

2.1.4. Use the JAWS Cursor and move through the screen contents until you find something that sounds similar to this:

   IPv4 Address. . . . . . . . . . . : 192.168.1.140

Whatever you find that closely resembles the above, that's your computer's address. Make a note of it.

2.1.5 type EXIT and press ENTER to close the Command Prompt window.

2.2. To find the address of the great unwashed Internet on which your router sits, go to http://www.whatismyip.com and look for something on the screen that sounds like this:

My Public IPv4 is: blah.blah.blah.blah

The numbers you hear, sepearted by periods, are your external wide-area network (WAN) address. Make a note of it.

Now for the hard part.

3. Using your router's address, which you can find by searching the screen you got in step 1 and looking for the string "Gateway," log into your router' administrative/maintenance account  and set up a forwarded port to the computer who's address you discovered in Step 2.1 above. The port number you will forward depends upon the kind of server you've set up. Secure FTP is port 22; https is port 443. How to accomplish logging into your router and setting up a forwarded port is beyond the scope of this mesage, mostly since all router manufacturers have different ways of doing it.

You're all set now. You can set up your internal file server to give you access to anything on your home system.

Note that some network-attached storage devices offer this ability in a nice, pre-packaged application which is a lot easier to set up than what I just described, except for the port forwarding part. That one's  a necessary evil unfortunately.