Here is how I do it step by step on my s8+:
Open Imgur App and select your albums
Select an album: (we'll use the first one)
Press and hold one of the photo's until you see this and click Share Direct Link
Find Copy to Clipboard: (You can stack multiple items in the clipboard so you don't have to go back and forth)
Paste on message board reply
Click the icon and get the final result
Click preview to make sure it works then post
I figure the Note has to be similar to this, hope it helps.