First you should check if you can upload files through the internet, without needing to get a seperate FTP program. By this I mean like how you upload files at Geocities, or upload attachments here.

If you can't, your ISP should have given you FTP info, like the server to connect to, username, password, etc. In that case, you'll need to buy or download a decent FTP program (CuteFTP is good). Then once you've put in the info and connected to the server, you'll be able to upload your files. Find the directory you want to upload the files to, and then find the directory where those files are located. (There should be two different window-type areas in the FTP program. One will show the contents of your HD, and the other will show what's in your webspace.) Just drag the files from your computer to your webspace to upload them. You can also drag files from your webspace to your computer to download them.

I hope that was helpful. =)