Linux, any distro, does not install software packages all to one directory, the way windoze does.
The files go to various locations. Usually the main program binary will be in something like /usr/bin and library files may be in /usr/lib. If you are installing a software package for a rpm type system, the package manager will tell you where the files go.
The package may, or may not create an icon in ( in your case )KDE menu. You can always add one. You need to locate the binary or script that launches the application, and then create an entry in the KDE menu, or you can create an desktop icon to launch the program with.
The desktop icon can be created by; right click the desktop, Create New, Link To An Application. From that point it is windbloze like, I'm sure you can figure it out.
To edit the KDE menu, right click the K ( start button ) and there should be a Menu Edit option. Once the application is launch, it is fairly straight forward to add application launch options.
To find a binary file ( program file ) you can use the locate command from a console. Open a console, and swithc to su, enter your root password. Run the command 'updatedb' and press enter. The first time will take a few minues, it is building a data base of every file on your system. Once this has completed, the command to fine a file is 'locate nameoffile'. Locate looks in the DB you create, not for the real file.
Hope this helps.