With this method...you can access your VSTi's from Channels>Add one or you can access it from your Step Sequencer by right clicking on a Instrument>Replace. Keep in mind, this is for VSTi's not VST's.
EDIT: There are a ton of free vsti's on the internet...just google it. Enjoy!
EDIT: There are a ton of free vsti's on the internet...just google it. Enjoy!