As most programs, You can simply do nothing but clicking "next", "next", "I accept..." and "next", "next" and "Finish".
During the installation You can change the directory in wich the ZoIPer Softphone will be installed.
Here is how the install prcedure should look like:
Here You can click on the "Change..." option, and the next window will be shown, where You can specify other directory where You want to install the ZoIPer Softphone:
After You have clicked "Finish" (and You haven't removed the mark on the "Lunch the program" option) the ZoIPer SoftPhone should appear on your screen. It sould look like this: