I agree with everyone else's sentiments, your rear sprocket is totally f*cked, so the chain and front sprocket are most likely in a similar condition. Don't d!ck around, heed the advice and replace them all with the best bit of kit you can afford - how long do you think you'll keep it? If it's only for a few more months then it wouldn't be worth buying a heavy duty O-ring chain (do they make them that small?)
The most important thing is realising that you need to learn to maintain your bike - look after the bike and it'll look after you. Buy a manual, some tools, and some chain lube. Sure, riding a 50, you're probably only 16 so we have to cut you a bit of slack, but neglecting your bike like that could have serious consequences as Ducatista's hinted at... You're never likely to be doing much more than 30mph, so traffic's going to be all over you, and were the chain to hop off and lock your wheel and spit you off, you could be flattened by white van man in the blink of an eye. The odds are stacked against us two-wheelers enough already, don't make them any worse for yourself. We all want to hear about your exploits on a 125 and getting through your test and everything, so make sure you're around to tell us about it ok? [smiley=thumbsup.gif]
Ah, just seen your post, been shopping, good lad :)
