How to complete a challenge?

What should be filled in the solution link (input field)?
I don’t know what should do.

Hi @htoohlaoo
Welcome to the forum. If you are talking about nodejs projects, it will be a URL provided by repl.it once you start ther server. Run the repl.it program and a browser window will appear on the top-right side of your page. Copy and paste the URL from that window to the solution link input field in your challenges. The URL looks something like this
https://boilerplate-advancednode.zaidali5430.repl.co