rules for valid amendments

i noted this comment in a previous post “3.  Generally yes, I think, unless something is moved as an valid amendment to something that’s on the agenda”

1.  how does one move a valid amendment  to something that was a motion on last ECM meeting? 

2.  how do I get the amendment to this ECM motion on the agenda of the imminent AGM. 

3. if the motion is already on the agenda for the imminent AGM, how do I move a valid amendment to it? (not sure if it will be on the agenda of the AGM – i haven’t received the agenda yet

and i’m new to the process so i don’t know if 3. is a silly question.

thanks very much.