I would start out by pulling the plug and looking for evidence of fuel. If none then look for reasons fuel would not be flowing. If the plug is wet with fuel then dry it off and reinstall and give her another try. After that I would check for spark. If you have spark and fuel, that's half the battle, now you just need compression and air... If this isn't your first motorized bicycle you should be able to tell if you have compression by listening/feeling the resistance of the motor when you turn it over.
It never hurts to try a different spark plug, most kits come with a spare, or even better try an NGK BP6HS or there is an E3 plug that Home Depot carries that works pretty good too.... I forget the E3 number, but if you need it I can dig up the plug I have in the garage that I tested and found it to run well, IMHO it was not quite as good as the NGK BP6HS so I changed back, but it did run well. I had to mail order the NGK plugs, so the E3 from home depot or the lawn mower section of any good hardware store may be the easiest plug to source....