How do I start a group chat with my Facebook group?

[Jacob R]

I created a Facebook group for my high school class that we all use very frequently. It has been very helpful. One thing I have been trying to figure out is how to start a group instant message (through Facebook's IM system) with everyone in the group. I remember I use to be able to do it easily a long time ago with another group, but I can't seem to find how to do it now.
The "Send Message" button under settings is not there.

[confused composing]

I don't know about Chat, since I never use one. There used to be group chat facility, but FB revoke it.

What you can do is make a 'group' Message (maybe it's the same way to do it in Chat, I don't know, as I never use chat). By 'group' I mean, you make a New Message and in the 'To' section, you can put several names, so the effect is like 'group' message, not the Group message though.