I use imgur.com, it's pretty simple and decent.

You just upload the photo to the share site, grab the URL for the pic from that site, and paste it into a DU post.

Note it should have an extension of .gif/.jpg/.png at the end of the URL. Without that, DU just thinks its a regular HTML link and it'll appear as just text in your post.

On imgur, the url to choose is called 'Direct Link'.

https://postimages.org/

Tap ‘Choose Images’
Tap ‘Photo Library’
Choose your photo from your Camera Roll or Gallery
Upload it by tapping ‘Add’ on the upper right
Tap the Copy button on the ‘Direct Link’ (second one on the list)
Paste to your DU post

Longer version: you have to find a image hosting service on the net. Post the pictures there. Then you have to get a link from that hosting service, and embed that link in you DU post using HTML code.

So there is nothing user friendly about it do I don't bother anymore.

That being said, Hugh and Happy explained it very very well!

https://postimages.org/

Choose image
Photo library
Select the pic
Hit Done
Once the pic appears go to the second line. Hit the icon on the right.
Go to wherever you are posting it and Paste