Just me problem !

Question

Hello, I want to change the default setting for the option: 1) Just me 2) every one in select installation folder and set the every one as default option, but I don't know how should I do it. Besides according to this option I want to set some data in different keys in registry I do not how can I get the user selected optionin the dialog and then use it for setting registry data ? Thanks in advance, Saeideh