The IP address you mention in your post is the one assigned to your PC by your router, not your public IP address supplied by your ISP. It will work anywhere within your private wireless LAN but not from anywhere on the internet - for it to work, you need to discover what IP address your ISP has given you. You can do this by opening the router's config screen in a web browser. The router will have acquired that IP addy, and it's that addy you need to set up with DYNDNS. You then need to do some jiggery pokery on the router to ensure FTP requests that come in to your home network are forwarded by your router to the correct PC, but as I've not yet tried to do that on my own WLAN I'll step aside and let someone else advise you.
