umm... i'm not sure i understand the question. you create a backlink to your website by placing a link to your site on another website, whether it is a forum, blog, social network, or any other kind of website. if/how different search engines pick it up is then up to each engine.
He is right yahoo backlinks are similar to Google backlinks. But yahoo too much like Blog Comment & post then the google .
Just do regular off-page - Forum posting, Blog Commenting, Directory submission and article submission and check your backlinks in yahoo, you will find your site backlinks increasing regularly. I am confusing either you asked how to increase backlinks in yahoo or how to check backlinks in yahoo. For the second question, answer is : link:http://yoursitename
Backlink is to link to your site from another website. Backlink in Yahoo is to link to your site from yahoo.
I guess you meant about Yahoo answers well then yahoo answers is one way to create backlinks. Just answers properly the question on the related category then just insert your site at the source upon submission.
You min can not find you site link in siteexplorer.search.yahoo.com. You need link form site which is already index in yahoo.com
in my opinion Google back links and yahoo back links both are same.first you can try to get more back links through various SEO methods like article submission,forums posting,blog commenting then this can help you to improve your site page rank in both Google and yahoo search engines.
Well, You can get high PR backlink from yahoo if you get in to the yahoo directory try that. OR you can also get nofollow backlink from yahoo answers.