How do I get the screen to un-freeze? I've done 5 out of 9 lessons and can't get lesson 6 to open
I'm not part of the tech team, but, if it is a tech problem on Duolingo's end, the tech team will need to know what operating system and browser you're using. (For instance, I am using Windows7/Firefox).
One thing you can try doing is refreshing the page.
Next, see if you've got a green check mark in that 5th skill. In order for a new skill to open though, you will need to have successfully completed all of the lessons before it. This means earning a green check mark under each of the lessons in a skill.