What does optimizing a website mean and how is it done?
Optimizing a website, also called Search Engine Optimization (SEO), means to put in the best words/phrases that match what the website is selling or offering. If you are selling kitty litter, for instance, you would want to use the words people use to search for kitty litter (aka keywords). This doesn't mean you could not have lots of other words that no one would use to search. You just want to make sure the main search words are on your site in various ways and as often as it makes sense to read.
Keywords could include: litter box, scoop, odor, automatic, self cleaning, pan, furniture, hood. You will notice I don't need to add the word litter in front of every word. Goggle searches all the words on your site so if it doesn't make sense in the sentence to add litter in front of the word, it isn't necessary. Google will put them together.
Another place you should put your keywords in in the title of the page. This is called the Title Tag (part of the Meta Tags) and is usually found, if using a Content Management System (CMS), in the admin area of your page. there is a field to fill in. If your site is not done in a CMS, then it could be in the code at the top of the page.
You can pick up some suggestions on keywords for your website by using the following tool: soovle.com
Type into the Soovle search box and you will see search word suggestions from many search engines.
To understand more about SEO and CMSs, go to the following posts:
Meta tags and how they are used
What is the best way to present the words on my site?
What is a Content Management System (CMS)?