Hi! There is a rosegarden package in the testing repo, so you can install it vis Gslapt. You need to add the testing repo -and probably you want to have the extra repo too- to your /etc/slapt-get/slapt-getrc. Edit that file as root and add this:
Save the changes, then you can open Gslapt, click the Update button and then rosegarden and other programms will be avaible to install for you.
You can use the slapt-get command on a terminal too, is the same.
btw, that file you have there is the source code, the standard process to compile sources is a)uncompress it to a temp dir, b)from that dir on the command line, type ./configure, you need to check the output of that command and solve any dependencie issue; then make, and then as root make install. You want to do this if there is no packages for you in the repo, or if for any reason you need to compile it with differents ./configure options.
Hope this help.