It has spring clips that hold it in the ceiling. When you pull down you're bending the spring clips. You have to be careful not to damage roof but you should be able to pull it far enough down to get one if the clips through.
However, you shouldn't be replacing the light if you don't know what you're doing.
Aceventuri t1_ixvp1sp wrote
Reply to Help with downlight fitting by ilostmyselfuk
It has spring clips that hold it in the ceiling. When you pull down you're bending the spring clips. You have to be careful not to damage roof but you should be able to pull it far enough down to get one if the clips through.
However, you shouldn't be replacing the light if you don't know what you're doing.