Create PWM with amplitude of +9v and -9v

Yes it is easy you need a split voltage supply of +/- 9 volts and a pair of transistors. What sort of current do you need to drive with this?

However I suspect that you don't actually want to do this so we need to know what you actually want to do and if this is the right way. So many beginners waste a lot of time asking for things that they don't really need, but theynonly think they need.