[TYPO3] What are "flexforms" and where do I change their "settings"???

[Mike]

Trying to follow this documentation:

http://typo3.org/documentation/document-library/extension-manuals/rgsmoothgallery/1.5.0/view/1/3/

It says "Configure the extension using the flexform settings – See the 
exact steps below (it is still very easy)"

However the "exact" steps don't tell me where the "flexform" settings 
are. There's no button for them in the panel here.

Also in the "Images from records" section is says "Add the plugin 
somewhere to the page and select “Images from records” in the dropdown 
in the flexforms."  Where do I "add the plugin to the page"??

m