Since yahoo is one of the most Popular Search Engine. So it can bring a high traffic to your site. To get listed in yahoo search you have to add your URL to Yahoo search. Yahoo has both paid and free submission option you may choose any one according to your requirements. You may even add you XML feed and all URLs using a text file. Generally they take 6 week to get listed but it varies depending on your site. Initially yahoo will crawl only few pages of your site then you will find that more pages are getting listed in yahoo. If you site is in yahoo directory then you need not to do all this things. To add URL You must have a Yahoo ID.