Battery needs to be charged fully.
Change plug and check for spark. You can do this by taking out new plug and put it in HT lead and rest the lead on the metal cylinder (or something that is earthed) and when you press starter then you should see spark.
If this is ok then pore a little amount of fuel in plug hole (only a little) and then put plug back in and press starter. Should fire on this.
billy boy, April 2009