To insert a new line without having too much space, use "Shift + Enter". Example using only enter:
line1
line2
Example using shift+enter:
line1
line2
To use the browser spellcheck and other tools, you can Ctrl+Right Mouse Button click and bring up the default context menu in the post editor, where the spellcheck is.
To use the encryption feature for PMs, it basically works like this:
When you send a PM, if you have enabled encryption and inputted a password(first input the password) when you press Enter, the message you send will be encrypted. If you untick the encryption, the message will not be.
The other person must also enable encryption and input the same password to read the messages.
Once you enable the encryption, it will reload the PMs with the password and decrypt them.