Hello I am pretty new to Steemit and Dtube love the platforms and community and want to keep using it. But I cant figure out how to claim my username. I just dont understand it says

"Now, you will need to publish your public key in your steem profile" I dont understand that how? I tried every key I have when I hit the confirm button but it always says its wrong. If you have setup on the new DTube Platform can you help me out and explain what they want to verify my username any help would be greatly appreciated. Thanks.