I can reiterate what has been said already, having dismantled a cheap fork myself - the time and effort you will likely expend aren't worth it. Probably better to just upgrade the the bike, definitely check out ebay, I got a great deal on my bike . If you really need to keep it, then it's not hugely complicated - if you look under the plastic caps on top, there's probably just a couple of long allen head bolts holding them together. Once cleaned and re-greased, it might go on working for a while yet. Then again it could be completely rusted on the inside and need replacing. Even if you replace the bike, if you don't mind investing some time, you could always end up with a usable 'beater'.