What are Page Properties? And where do I find them?
"Page Properties" is a nice way to refer to Meta Tags and the Title Tag of a web page. When you click FILE-> PROPERTIES, you will open a dialog box that contains a place for you to enter your meta tags and Title Tag. (See the image below)
Every Single Page needs a unique title and description. (Keywords are optional. Most search engines don't use them anymore.)

Click on the image to see Page Properties
What are Meta Tags?
Meta tags and the title tag are placed in the head section of your web site. Info in the <head> section is not visible in a browser. The exception to this is the Title. The Title is visible in the upper left corner of a browser. The Title is also the name of the page in a bookmark when someone bookmarks a web page.
Search engines use some of this info, therefore, it is so important to complete the Title, Description, and less important to complete the Keywords.
Meta Tags play an important role in SEO (search engine optimization). Expression Web's 'Page Properties' feature enables you to quickly enter a title for the <title> tag of a web page, and to enter Meta Tags (i.e. write a page description and keywords)
The Title is very important to SEO. As a result, you should research Keyword phrases that relate to your page content and use them in your Page Titles.
Every web page should have a unique title that is relevant to the content. Likewise, a unique and relevant description is also vital.
Meta Keywords are pretty much useless. However, I still fill them in because a few of the small search engines still use them.
What is far more important is to use Keywords throughout your content, in the title tag, and in heading tags.
The title tag, <title>, should never start with "Welcome" or "Untitled".
Yet if you did a search for "Welcome" or "Untitled", you will find millions of search results because too often, people neglect this portion or they don't know how to enter this information.
Use keywords in your title that people might type into a search engine. But Remember: The title needs to be relevant to the page it is intended for. Don't get yourself banned from search engines by trying to use keywords that are not present on your page merely to get into the search engines results pages. Keep it natural and on topic.
Each web page needs it's own title. So enter Page Properties for each page.
DO NOT ENTER PAGE PROPERTIES IN A DYNAMIC WEB TEMPLATE! Every web page must have a unique title and description. Plus, you run the risk of locking out the Page Properties of the pages you create from the Dynamic Web Template.
The description is the portion of a search result that people will read and decide whether or not to click on your site in the results pages of a search engine.
For instance, say someone types in the "Expression Tutorials" into google. Pages of results will be populated and take notice of all the links and descriptions that come with each link. That is what the description is for.....to describe what is on your web page, thus, help people to chose your link.
Again, keep the description relevant so you don't tick off anyone! No one likes to click a link and NOT find what it says it has. This is the best way to drive traffic away from your site.
Keywords are optional since search engines no longer use them to find your web site. Keywords were so badly abused in the past, and search engines responded to this abuse by changing their algorithms.
However, I still recommend completing the keywords because there are a few search engines out there that still use keywords to determine their search results. I just don't place an emphasis on keywords.
Please use heading tags to break up your content. Then write excellent headings as that is the key to being found in search engines. Well, that and a few other things. Use at least the <h1>, <h2>, and <h3> levels of headings. Then style each one with CSS so as to decrease the size of the font. An h1 is huge by default. We don't want huge. We want presentable and readable.