On the forum page that you're looking at right now, Click on your user name up at the very top right of the page - next to the "All" button by the search box.
A very brief profile page will appear. In the middle of the page is a small list: Member Since, Last Seen, User Level, Subscriber Only Skins [Click on that]. You'll go to your subscriber skin page.
If it's a .suite or .theme files, after you download the theme, you can right-click and "open with" WinZip or such, or rename the extension to ".zip" and open it to extract the pieces you want - the suite files are just zip files with a different extension.
Sorry for my lack of screenshots.