I haven't really used Dreamweaver, but the main thing your gona need from either whoever hosts your website or the people who now look after it, is the FTP details; the server, the username and the password.

Dreamweaver should have some way of saving that information for uploading via FTP. Or you could download an FTP client manager program such as FileZilla and enter the FTP details in there, using that program to upload your files to the website.

This is a fairly basic request so there should be plenty of help on the Adobe website. In fact, heres a link:

http://kb2.adobe.com/cps/147/tn_14787.html

Have fun with your website =D