Hello Ron,
Welcome to Terragen and to the forums!
Regards to your system, I would definitely recommend reconsidering an upgrade. I would also switch to a desktop and use the laptop for tests or other kinds of work. Not a stranger to being cash-strapped myself, the price of cpu's has dropped dramatically in recent years and you can get something quite decent for even under $500. My current system is a quad core 3ghz, 6GB of RAM that I purchased refurbished off the Future Shop site for $400 3 or 4 years ago. Not impressive stuff, although it was considered half decent at the time and handles TG 3 adequately, although not spectacularly, even today.
And yes, the forums will be instrumental in your further TG education.
In the meantime, I'd recommend sticking to using the tabs at the top of the Terragen screen until you grasp the handle of how to use the nodes adequately.