How to add a program in Ubuntu:
Ubuntu 9.10 comes with an add/remove software called: Ubuntu Software Center.
This software can be found in: Applications => Ubuntu Software Center. Once started, you will find a list of available categories and a search box; you can navigate the categories or use the search box to search for your software.
Once you locate a program you would like to install, click on it => then click on the Forward arrow button found on the right side of the software you just clicked on => now click on the Install button => then enter your password to begin.
How to remove a program in Ubuntu:
To remove a program in Ubuntu => start the Ubuntu Software Center => click on Installed Software (located on the top left) => click on the software you would like to remove => click on the Forward Arrow => then click on the Remove button.