i put it in the maps folder and run it its going through the video and stuff than its says gathering exception data.

Biohalo is a single player level,you get exception becaouse you cant load it as a multiplayer map.there are two ways to make it run:
1)Download Bitterbanana's alldev trainer and when turninig on halo press ~,write map_name *name of map
http://hce.halomaps.org/index.cfm?fid=1099

2)Press the right mouse button on halo,than proporties (if it is in the english windows,i have hebrew one)and type in the end of haloce.exe -console
-devmode and than you could map_name *name of map

I suggest using method 1,its easier.

you don't actually need to have dev on, i don't think.. just the console.
so if I'm right, for method 2, you don't need the -devmode bit it should just be -console.

Correct. press this "`" key and type in map_name biohalo then press enter.

i did i have -devmode -console and the map loads and its showing the camera moving through the streets then crashes.

you need console or devmode.

simpy press the ~ key and enter map_name(name of map here)

You need at least console. If you just have devmode, then you don't get the console.