Rudimentary Dot and Dab Question

I need to put up some plasterboard when i have take off render and wish to dot and dab it but i am not too sure how to 'hold it' whilst it is going off?

All of the D&B bits i have seen have been from the floor up, this bit is about 5 foot in the air

Anyone know how to do this? Does it just stay there and go off without moving or would it need to be held in somehow

L

 

pin a batten to the wall first

 

How thick/thin does the batten have to be for this?

 

I don't have a great deal of space to put in a batten. Is it possible to D&D and then screw into the cured mix?

 

This is where i have exposed some brickwork, and want to put some plasterboard so that it can be replastered