Somewhere in the documentation for Blubster (if any) there should be a mention of what port it likes. Try the help file, their web site, etc. Then go into your router's configuration app and forward Blubster's port through to your PC.
Then, before you try ANYTHING with Blubster, get an industrial strength antivirus program, install it, tell it to be hypercritical and extremely suspicious, then cross your fingers. Peer to peer networking software has become the darling of the virus writing crowd, so using it without "protection" is... well it's very bad for you.