as far as i know, clockwork is installed, how can i check m8?
If it's all installed correctly then if you turn off your phone, turn it back on whilst holding the volume down button, keep the volume down button held, and you eventually after the green android logo you should see some upside down text (think it says clockwork?), you can let go of the volume down button now (think you only need hold it down for about 5 secs actually). It should eventually load up the clockworkmod menu (it looks really basic). Since you don't have a rom yet you can select the option to reboot device to restart your phone normally again.
Oh, and you use the volume up/down buttons to navigate the clockwork menus and the home button to select an option.