IMing someone

[Jstr]

How do you IM someone

[Powerline]

Do you mean PM or VM?
If you want to IM then just add them to their messengers if they have it provided on their profile.

[Origami]

IM - This isn't Facebook, add them via WLM, Yahoo, or Skype.
PM - Go to their page and click this button under their "Contact Info" tab.
http://screensnapr.com/v/CDBwxf.png
VM - Go to their page, it's on the front tab. Just type and post.

[Jess]

Quicker way to send someone an IM is clicking on those icons, if any, below the rep blocks. that is if you mean sending an IM, not PM or VM