I'm very confused about how E2E works?

This is more of a general question, but when I am issued an E2E password, what do I actually do with it? I can’t see any other users’ posts in either phone or browser while in an encrypted chat…

E2E is beta. Not currently supported on mobile. But when used your messages you send will be encrypted in your browser using a key that is generated in your browser that can be loaded back on other machines using the password we ask you to save.