Answer 1

Go to your profile by tapping your profile picture. Tap the little green + on the bottom-right corner. Write your challenge. Post it. Tap on share, top-right. Copy to clipboard. Refer to https://www.sololearn.com/Discuss/1270852/?ref=app. Comment, pasting the link to your challenge's post.

Wait a couple of hours and now you have succesfully lured ~10 people into pressing their keyboard buttons shifting bits left and right to solve your challenge :)