(Help) Buying Xbox 360 Live (Help)

[deadly serious]

I didn't know what section to put it into for console gaming help.
I've put a new credit card onto my xbox 360 account and changed all the details etc but I don't know where to buy the xbox 360 live time from. Can someone tell me step by step directions on where to purchase it on the xbox dash or online?

 

[New Defied]

I'm on my phone right now, but I'll be home soon. If you havent already figured this out, shoot me a PM and I'll walk you through it when I get back.

 

[Proc]

I think the only way to add time without buying the physical card from the store is to run out of gold time, and while having a silver membership, there should be some kind of option for "upgrading" or "upgrading to gold".