Park have done all the work for you..
http://www.parktool.com/repair/readhowto.asp?id=65
If it's not like this and it came from a shop this way, then you should get a new headset from them because if you've ridden it like this for a while the headset will be fucked/pitted.
@hippy started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
Park have done all the work for you..
http://www.parktool.com/repair/readhowto.asp?id=65
If it's not like this and it came from a shop this way, then you should get a new headset from them because if you've ridden it like this for a while the headset will be fucked/pitted.