Log in and you will see at the right hand corner a box that says chat box. Click on it and start typing.
Through instant messaging or wall posts
First you have to go to www.facebook.com and set a profile up.once you do that you will have to confirm you facebook profile at your email address.once you do that you can find friends send messages to friends.once you have friends and they are online in bottom right corner it will show the friends online you can click on their name and you guys can instant message one another.it's not that hard...I know you can do it!!
First you have to open an account with a few details and find your friends and start talking !!!
On the bottom right of the page there is a little grey rectangle, press that and a list of people online comes up, click on a name and another box appears, type something in there, press enter and it sends it to the person