Like almost everything in MODx, there are various ways to do it...
In the manager you can create a folder by making a document a container.
You can create a Template Variable and give it an image input type and
when you create a document with the template that you assigned the TV to,
it will open the resource browser where you can create folders and upload
images.
The other way is to install one of the many gallery snippets found in the
extras section and in the forums, like MaxiGallery, Direct Resize, etc. which
give you different characteristics to manage and display your images.
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