If you prefer a GUI for your FTP clients, you can open the file explorer (the folder icon in desktop mode) and enter ftp://servernme.com in the address bar. Also, a developer has released a free FTP program on the Windows 8 Store.
mFTP opens to a simple interface. You specify the server address, username, password, and port (21 is the default for most FTP servers). Once logged in you can browse through your folders. To upload a file, right click or swipe up from the bottom of the screen. Select upload, then choose your file. In the lower right, click “Open” to begin the upload.