1) Unpack the tar.gz file somewhere using tar zxvf synce-gnomevfs-0.13.tar.gz
2) Go into the newly created dir by cd synce-gnomevfs-0.13/
3) Read installation instructions in the README
3a) ./configure --prefix=/path/to/installation directory
3c) sudo make install
Edit: just out of curiosity, I checked if there is a Ubuntu package for Jaunty and I found synce-gnomevfs version 0.11
. Unless you need some specific feature available only in newer versions, you can install the binary package using the Synaptic software manager. The universe repository must be enabled.