To allow new tags in your content body you will need to configure the Input Formats and list the tags you would like to include. To allow images in your pages you will need to update these filters.
- Navigate to Administer > Input formats.
- Click on "configure" next to the input format you would like to update. Mostly likely this will be the basic format of, "Filtered HTML."
- At the top of the page, click the "Configure" tab.
- Scroll down to "Allowed HTML tags"
<img>(with the angle brackets).
- Scroll to the bottom and click "Save configuration."
If you have other elements that are "disappearing" when the page is displayed, check the "Allowed HTML tags" field to see if there are other elements that need to be added to the list of allowed tags.
For more information about Input Formats, please read Text filters and Input Formats.