On the top menu go to Mambots --> Install / Uninstall. You will see now a list of mambots already installed on your site. Under that list you will see "upload new mambot" section.
(under that you will see a list of directories. be sure that all that directories are writeable)
Press "browse" and go to package you want to install. Select it and upload the file.

The next screen will show you if the mambot was installed succesfull.
Go to Mambots --> Site Mambots and publish the new installed Mambot.

Thats all for now. In the future there will be tutorials about how to configure different mambots for your Joomla site.