As I understand it (and correct me if I'm wrong), you have free wifi in your place, thus disabling your Time Capsule's wireless radio but still connecting to it via ethernet, while connecting to the free wifi for your Internet correct? If that's the case, and if your Time Capsule is indeed NOT part of the free wifi network, then the only way you'll be able to see your Time Capsule is to either disconnect from the wifi (turn off AirPort or disconnect from the free wifi network), or temporarily move your ethernet connection to the top of the priority list in your Internet Connections. The problem with either is that you won't be able to access the Internet while you're connected to the Time Capsule for what I assume is backup purposes. If you wish to continue using the free wifi and Time Capsule simultaneously, you'll either have to bridge your Time Capsule to that router or join as a wireless client. As far as I know, it's not possible to connect to two networks at the same time.