Free 48hr/2 day Xbox Live Gold Codes requires Xbox live/Windows Live account
Next click on the xbox button(2nd image)
Sign into your Xbox live/Windows Live account (the site live.com is owned by microsoft, it is ok)
Once signed in you will receive 2 codes the top code is your 48hr gold code (3rd image), the bottom code will only work in Japan so forget about it.
You can get multiple codes with multiple accounts.