You can setup your account here and learn more: http://help.bingads.microsoft.com/apex/index/3/en-uk/51093/
The good thing about Bing ads is that they now work with AOL and Yahoo as well. I would give them a call, they have a very very good support team that will help you go through the menu of advertising options. There are many choices that will save you a lot of money too depending on what you want to accomplish (For example: Advertising only on Microsoft Network site, or allowing your ads to show up on other networks as well). Good luck
Simply create an account and contact their support manager. They will fully assist you, how to create your campaign.