The problem with the apt-get route is that those packages are generally behind -- sometimes far behind -- the latest source code. The upshot is that using apt-get is very easy. So following @Avi's advice will lead you to any number of quick ways to install Radiance via apt-get
.
If you wish to use the latest features and fixes in Radiance, I recommend you grab one of the packages we maintain at NREL, here: Radiance Releases at NREL's GitHub Repository. For Linux, we offer an archive of the executables, library files and all man pages (documentation), and these are built using Ubuntu. This is not an "installer" per se; you will have to install everything yourself by unpacking the archive, copying everything to a proper location, and setting a couple of environment variables. There are loads of resources online for help on these steps.
The last statement in your post -- "and I want to know how to run radiance program" -- is a doozy, however. Following the install steps will get to you where you can "run Radiance", but "running Radiance" is not a matter of double-clicking an icon and poking around in menus. Radiance at its core is a series (dozens) of executables that are to be used in a pipeline, following the "Unix Toolbox" methodology. This part of your question is really about twenty different questions, to start with. I suggest you have a look at the tutorials here, as you begin your journey toward lighting simulation enlightenment. Pun totally intended.
In particular, Sarith's new tutorial on the many different matrix-based annual simulation methods is spectacular, includes full command sequences and all example files: Daylighting Simulations with Radiance using Matrix-based Methods
P.S. NREL is updating our Radiance-Git repository to allow for automated building/testing; we hope to merge in all the updated Cmake build scripts, documentation thereof, and post regular build/test results to a dashboard early in the new year.