There is no C: drive in OS X
The default programs place is the Application folder.
There are a couple of methods to install a program.
You can drag and drop the icon as for Thunderbird in this example
or double click the box icon as for Safari in this example and follow the on screen directives
To remove a program simply trash its icon. In some cases you can find an uninstall icon. In some cases trashing the icon is not sufficient to completely remove the program.