Organic Search Engine Optimization (SEO) for website promotion is hinged on the TEXT content of the pages as detected by the search engine spider.

organic SEO rule #1:

If it's not visible as TEXT on the page it is not a keyword or key phrase. Pictures of text are not text, even though search engine spiders are getting more intelligent they still can't read text presented as an image.

try this simple SEO exercise:

Open your page in a web browser, under "edit" choose select all, copy, and then paste it into a text editor (like Notepad). The result is the text of your web page and you may be surprised by the results.

Keywords or key phrases should be placed in the title tag, description tag, header tag and appear very close to the top of the page content to be effective.

If you can't figure out the keyword or phrase from the content of the page, I suggest splitting the content between two or more pages that are relevant to their respective keywords or phrases. Covering too much ground on one page will only dilute the effectiveness of your organic search strategy and make it difficult for visitors to find what they are looking for.

use common language for your keywords and phrases

Remember, the search engines are trying to return the most relevant results for the user. Use keywords that are commonly used in regular conversation. Even though the words "Bipedal locomotion" and "Walking" mean the same thing, a recent search on these words on Google returned the following results:
For "Bipedal locomotion", 28,400 results.
For "Walking", 342,000,000 results.

what is organic SEO?

Organic SEO is not magic and it's not cheating. Proper search engine optimization is simply ensuring that the code that creates your web site is working with the search engines procedure for ranking web pages that contain content relevant to the users search term.

Next time: html tags and uses for SEO explained:

Introduction to Website Promotion Article Series
Website Promotion using Organic SEO, Rule #1
Website Promotion using basic HTML tags in SEO, Rule #2