If you are in a country where spread betting is allowed (Europe, Australia) you can trade Forex using a spread betting platform. However, this route will not give you the free charting software and the ability to use robots.
The way to go is to open an account with a specialist Forex broker that offers the charting software called "MetaTrader 4" for free. This is the package you need because it is the only platform that allows robots (called Expert Advisors) to be used and if you have the ability you can also build them using the same platform.
As I am based in the UK I have an account with Alpari (see below) who fulfill all the criteria I have mentioned. Check the list below for brokers that support MetaTrader 4 depending on where you live.
The first stage is to go to the broker site and download and install MetaTrader 4. When you open it you will see that you will have a demo account and everything in place to trade starting straight away.
Having got MetaTrader up and running you can then think of buying (or building) and using robots.
You can then add a live account if you wish when you are ready.