So, you came! Well, down below are many ways a lot of things will get easier such as scrolling, platforming, etc.
1. Enabling the Player to Move
Well, the easy script is

when [whatever] key pressed
move (blah) steps

1 1/2. Enabling the Player to Move (Improved)
This is a better function to letting the player move.

when green flag clicked
forever
    
if <key [whatever] pressed?> then
move (whatever) steps
    
end
end

2. Platforming (Simple)
Well, a simple platforming engine? Here you go:

when green flag clicked
forever
    
if <not <touching color [#f0f]?>> then
change y by (whatever)
    
end
end

3. Scrolling (Easy)
Need easy scrolling? No problem.

when green flag clicked
forever
    
set x to ((scrolling) + (480))
end

and you also need

when green flag clicked
set [scrolling] to [0]

4. Death Sensing
This is how I sometimes do it.

when green flag clicked
forever
    
if <touching color [#f0f]?> then
stop [all]
    
end
end

Want me to add more? Just Ask! It's not that hard!

when green flag clicked
forever
    be awesome
end