To install iZeit for the first time, upload all files to your server then go to http://yourdomain/path/to/izeit/ to start the installation. You'll need your database details.
Before you proceed with installation, it's necessary to change the permissions on the /includes/ and /includes/data/ directories to 777. On Unix, this can be done using the CHMOD utility from the command line, Windows users will need to grant 'Everyone' permission to read and write to the directory.
Changing permissions can usually be done using an FTP client.