There is an expert from each engine that moderates each forum. These are very heavily trafficed forums with tons of information. Meta description tags are also important, since they are often used by the search engines to describe your pages. Here is another great tutorial site. Use the ALT image tag.
Many people still turn images off on their browser.
This is a good place to legitimately put more key words. Sometimes just a few more keywords can put you on the first page of the search engine. The color of the border will be the same colors used in your text hyperlinks. If you have your best keyword phrase appear there a few times, and then repeat it regularly throughout the normal text portion of your document, then chances are that your page will do well. The number of quality links you have into your site plays a key role in Search Engine relevancy algorithms.