help! how to register a systemd service for starting X-window

view story

http://forums.fedoraforum.org – I 'm using fedora 17 but not used to GNOME 3 ,so I uninstalled gnome desktop environment (including GDM login manager ) . For now , when the system started, it can't enter the X-window(I'm using awesome WM without any desktop env) and the tty1 is absolutely black without any cursor or word ,thus I have to press ctrl+alt+f2 to enter tty2,then login , then issue the command : startx ..... it will jump to tty1 and show X... so , my question is :how can I register a service in systemd to start X-window automatically ? I wrote a file named startx.service in /usr/lib/system (HowTos)