I'm getting Bannasplits better cities mod so I downloaded Wryebash, it is recommended that you install it with Omod. What is Omod and is it already installed into Wryebash?

You need this program OBMM = Oblivion Mod Manager (link below). Its a program you need to run omods, and makes installing of mods way more easy than manual soo......

1) Download and install this : http://www.tesnexus.com/downloads/file.php?id=2097

2) Find "Bananasplit Better Cities" and download the omod version, and open with OBMM.

the omod is a file format (compressed) that Oblivion Mod Manager uses.

It makes installation and uninstallation of complicated mods very easy, but you need to follow a few steps - see post above by TzToppDog for links etc.

Everything you could ever want to now about the http://lhammonds.game-host.org/obmm/default.asp format.