Creating sitemap for Yahoo is very easy and it supports only .txt file under urllist.txt. You can directly submit it here: Submit to yahoo
You can also authenticate your personal blog here. You must have yahoo id to submit your site map and authenticate your ownership later.
Step-by-step creation of urllist.txt :
1. Click on start > Run > Type notepad.
2. Paste all the url of your website want to be indexed in Yahoo.
3. Upload it at the root of your site directory.
4. Open the page siteexplorer.search.yahoo.com.
5. Add your web site or blog in “MY Site” and then click on “Add My Site” button.
6. Enter your user id and password and then click on login (Register for new yahoo id if you have no id on yahoo).
7. Click on Authenticate for your ownership.
8. To verify, Yahoo will suggest you to create a .html file and put string inside the file.
9. Upload this file in the root of your site directory and then click on Ready to Authenticate.
10. In the case of blog, use add Meta tag option. Add the meta tag in the head in your blog and then authenticate.
If you want more related help then visit this page Yahoo Helper