I'm beggining to understand how forum gold is used but what can I do with it as far as cash? Is it only good for trading or can i turn it back into cash?

You cannot turn it to cash, it is a virtual value used for trades in different games etc.
What you can do with fg : http://forums.d2jsp.org/info.php?p=37

only trading vs ingame items of multiple games

if u donate to njaguar u may gtet df forum acess where u can trade your fg real life goods other users offer

It's the currency of the site, used to trade mainly but you can also buy things for your account like orbs and media slots.

Wow! bummer. Thaks for the replies but you would think there would be a way to post items and then get forum gold without having to give hard earned cash. :/

Isn't it intended to buy d2 items ?

Yes you can make a trade topic offering your items for FG.

Choose your realm here: Trading Grounds and start offering items.
Also check this out:

• Trading Rules
• How to trade
• How to request a Mediator and prevent scams

This could help, too: How do I get Forum Gold?

Trading,Profile effects etc

Just buy in game items with it