I have downloaded the alternative start mod for oblivion, I put it in the data file and it shows up on the checklist on the oblivion launcher. I have ticked the box yet it doesn't work, can anyone suggest how to make it work?

Post your load order? And perhaps download and run BOSS, and read any warnings/notes it gives you.

Eh? I'm a total noob what does that mean

In that case, I suggest you read the sticky topics, especially the FAQ and the "Compatibility and you" thread.

Also, try using the Oblivion Mod Manager to install mods instead, it will make things much easier for you.

What version of Oblivion are you using?