At the risk of appearing unhelful, the Smart FTP site has lots of actual info on using the product.
The homepage is click here and a list of 'how-to' articles is click here
In essence, what happens with FTP is the web host/ISP/network manager issues a Host Address (location on or name of web server), username and password to access the account.
Often this may be the same as the domain name or it may be something completely different, depending on how the host has their servers set up.
You create the connection in the FTP program to the web server and when it successfully connects you will normally get a Windows Explorer view of the computer you are on.
Browse to and highlight the files you want to upload and clck the upload button.
Unless your web host tells you to upload to a specific folder or you have file/folder permissions to set up or FrontPage server extensions to worry about it really is that simple. The hardest part is often creating the connection to begin with by inputting the correct Hots Name, User Name and Password.