Yeah, i am still very confused...
This is what i got: (as you can see i am using local folders to store the images)
<<set $random to random(1,5)>> //setting the random variable
random is:$random //Printing random var
[img[images/$random + ".png"]] //Suggested solution, here i get nothing, not even a broken link
<img src="images/$random + .png"> //Testing since i am using this method to display images. Displays broken link
<img src="images/1.png"> //Static display of image to verify, works fine.