Hi guys can someone help me how to optimize my website rankings on different search engines. Please I really need to know.

Start by reading WDG's feature article Improving Search Engine Rankings.

Is there a specific html code I need to use for my site to be on top or second rank. Please I really need help I already edited some of the meta tags and description that we use but still we are on rank 9 at yahoo search engine

It's not only the keywords and description that make out how you are ranked. Have you read the WDG article? AFAIK, it has advice as well.
And there are many more articles on the web on the subject, http://www.d.umn.edu/itss/support/Training...gation.html#seo.

Please see the FAQ entry Is there a way to get indexed better by the search engines?

If there were everyone would use it and status quo would remain.

Also read Google's information for webmasters. Hint - it ain't in the meta tags!
http://www.google.com/support/webmasters/

Besides, a rank of 9 seems not bad at all.
You might consider AdWords.