I want to sell name brand on my site Do I need a license?

If your use is truthful and you are selling authentic products, then yes you can use the brand name on your site to describe the goods. The Lanham Act (the US trademark law) specifically allows uses of trademarks when the marks are used for the purpose of identifying or describing the owner. There are limits, however, so you should contact a trademark lawyer to make sure your use is a fair use under the Lanham Act.

If I understand your question, you merely want to use the trademark for the product you intend to sell on your website, e.g., PUMA for PUMA brand T-shirts.  So long as you are using the trademark to identify genuine goods of the trademark owner, no license to do so is required.