There is a button that says "Login" in the menu at the top, clicking this button will take you to the login page, where you can login. Here you simply input your username, and your password and the amount of times you wish to stay logged in for.
You can click "Log Out" in the menu if you have logged in, logging out can clear cookies related to your account information, which is a recommended safe way when you are using public computer.
By clicking on the "Search" button in the menu. Then inputting what you wish to search for, you can restrict where you search with the drop down lists.
First click on the P.M.
button in the menu, another window will pop-up, from there you can access the "Send a U2U" screen, by clicking on it at the top. Place the users name in the "To" field, and then insert a subject and a message and click "Send".
You can view all the members by clicking on the Members List
button in the menu.