How do you turn on your pocket bike without pull start?

I'm going to assume you are talking about a pocket bike that has a non-functioning pull starter? If so, you have a problem, since most such machines have centrifugal clutches that don't engage unless the engine is turning faster than a pretty good rpm, so they can't be push started.

New pull start assemblies are pretty easy to find on the internet for quite reasonable prices, and are simple to install. Do a little research and you should be able to find one.