As far as I understand you would like to create pages programmatically and add some html content to this pages and you will get the information from an external database.
Please note that in Sitefinity we display content on the pages using widgets. If you create the page from the Sitefinity backend you can drag and drop different widgets depending on what you would like to display on the page and place the widgets on the desired placeholders.
When creating the pages programatically if you would like to add some content on the page, you will need to add the control to the page programmatically.
In your case, if you would like to add an html content on a page, you need to add a Content Block control to a page programatically and add the desired html in the content block. You may refer to the following article
from our documentation on how you can add controls to a Sitefinity page. You may also refer to the whole section form our documentation
for adding and removing controls to a page at the following link
Here is also an forum thread
where you can find sample code for adding a Content block to a page using the Fluent API.
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