How do you get online with the gold membership card for xbox 360 and also get to the xbox live market place?

I also dont really get what the silver membership does? Could you please put it in full details Thx alot x10 i f you could help.

First you have to be connected to the internet to even put your gold code in to create an account, once you have that down it will take some time for the updates since im guessing you have not seen the new dashboard. all you really have to do once your on the dashboard is really just use your stick to scroll up until you find the XBL Market place and if your trying to redeem a micrrosoft point card do it on either xbox.com or go to your dashboard and go to redeem code and you will get it from there