Well i got fedora 8 distro and want to install it on fedora 7 ,Well at the first place is there any room for that ?
well if it is then how can we do it ?

Yes you have room for it.
Select "upgrade Fedora" to do it.

wold be glad if you could be a little more explicit in telling , how to do it ...?

Boot from the cd and when the installer asks you whether you want to upgrade or do a clean intstall, choose upgrade

ohh. its that easy ..
well since i have already a dual os , i guess it will not create ne problems .

wold be glad if you could be a little more explicit in telling , how to do it ...?

Sorry for not saying that explicitly, and if you have dual OS then no problem would arise as long your boot-loader is installed correctly.

well thanks for being so concerned . i am on my way on installing the new version (hopefully the new one ) . thanks for help