I'm trying to make a game for Christmas and I need to figure out how to do something like “If backdrop=2, show, if else, hide” but I can't find anything like that. Please help! Oh yeah, this is for a chest sprite and I can't have it showing in the beginning.

Create a variable called backdrop.

if <(backdrop) = [2]> then
    show
end

if <not <(backdrop) = [2]>> then
    hide
end

I made a project, where you can test it:
http://scratch.mit.edu/projects/38306992/
Look at the code and test it!

Good luck for the Christmas game!

Another way to do it, which would be easier, would be:

when gf clicked
forever
if <(backdrop name) = (example)>
show
else
hide

An easier way to do this would be “if backdrop name = ”so-and-so“. Or, just ”if example = “#”. However, I'm still new to making these scratch block things in forums, so I illustrated with the example above.

Another way is

when green flag clicked
hide

when backdrop switches to [backdrop 2 v]
show

Thanks guys! I always didn;t know what the green was for!

Oh yeah, I have another quick question:

Is there a way to put. if sprite1 touching sprite2, sprite3 show?

You have to use a broadcast:

if <touching [sprite2 v]?> then //put this in sprite1
broadcast [show sprite3 v]
end

when I receive [show sprite3 v] // put this in sprite3
show

or a variable:

forever // put this in sprite1
set [touching v] to <touching [sprite2 v]?> // this sets it to true or false
end

forever // put this in sprite3
if <(touching) = [true]> then
show
else
hide
end

Like

if <(backdrop name) = [2 ]> then
show
else
hide
end

Thanks again, guys! I should be good for now, now.