it can't be that hard, but I see no way to reply to a PM. I've been starting now conversations instead, but that sucks. Maybe it's a Chrome on an IPad issue, will check the computer later today.
I am having trouble as well. The "write something" box is not present in the Inbox. Viewing from an iPad on Safari. Will check from my phone and post again.
NVM figured it out: Have to click on the message subject line to bring up the whole conversation along with a reply box.