I am making a cms for a booking app and the admin will be able to see the number of bookings at any moment.

How can I do it so that the above updates continuously with ajax...like facebook newsfeed for example.

So far the only ajax I have made is based upon clicking events...but this is something different I think.

I believe you're looking for websockets, however I haven't got a clue how it works, or how to implement it. I just read about it the other day and never tried it out.

Try starting here, after that I'm not the best person to point you in any direction on this subject.