I heard that you now could mod on your xbox with the lisence tool, but how can anyove give me a link or a step by step walktrough please

You can't mod anything with the http://www.xbox.com/en-US/support/systemuse/xbox360/licensemigration/faq.htm. You can't use player made mods on the 360 no matter what. You can only buy the official ones from the Xbox LIVE Marketplace.