is possible and if so how!!!
please explain in dummy form!

If you're asking for us to explain backdrops in a Scratch project then here's the answer but if we misunderstood then sorry!
Click on ‘Stage’ to the bottom-left of your Sprites ‘area’ and then the scripts will come up. There's a tab above that ‘Scripts’ box with these options: ‘Scripts’, ‘Background’, and ‘Sounds’ in that order (well, we have Scratch 1.4 so if this is wrong, sorry!). Click ‘Backgrounds’ and from here, you can edit backgrounds you have made, import backgrounds from already in Scratch, paint new ones and delete backgrounds you don't need or want. Once you have backgrounds you can start writing Scripts for them, such as when they change over - and of course, being Scratch, that is only one of MANY different things you can do!
Hope this information was helpful - greenmoonfriends

how to change:
Go into ‘Looks’
Take one of these blocks out

switch backdrop to [backdrop1]

or

next backdrop

guarded by (Greg the Evil Kumquat Guard)