It would be best not to do so. The Traders Forum remembers various things about you in your user profile, and can detect things such as new messages received since your last visit. If someone else logs into your account and reads the new messages, you will miss a lot of interesting discussion.
Accounts are free.
Let your friends create accounts for themselves. By clicking on the top title, you will see ALL of the messages in that topic. I added a message a little while ago. No, your message relayed just fine. The login name associated with each message shows up as a link.