This link will take you to a cool site where you can create a google xml sitemap.
The google sitemap has various settings but just the simplest way is to just enter the URL of your site and let it create google site map for you.
Then just upload it to the root of your site and using google webmaster tools, tell google about it.
PS: Yahoo is so crap. Never use Yahoo's online advertising system. I will not go into it right now, but trust me. It is not worth the trouble.
Anyway. Get generating your google xml sitemaps.