so a lot of people like me when I started were confused with how the custom blocks work this is a simple guide on how it works
this probably has been done before but I'm trying to help

ok so if you go down to “my blocks” and you hit create a block, now what. well its simple just name it about what you want it to do
EX:JUMP

I know this may be obvious to you but it is important because you don't want blocks getting mixed up.

now you have a block you don't need to worry about the boolen inputs they don't do much,
a define box will appear this is how you use it, put other blocks attached to it and when you grab the block it will run those commands as if it is a regular block

EX:

define JUMP
repeat (10)
change y by (10)

end
repeat (10)
change y by (-10)

end

\
so now you can just go

when [up arrow] key pressed
jump

now this may seem pointless but for example you need to create a trampoline
normally you would need to type out the code to jump again but now you can just go

when green flag clicked
forever
if <touching [trampoline] ?> then
jump
end
end 

hope i helped in any way

Woah, a signature! :: control

Hi! It's great that you want to offer some useful tips to other users, but this forum isn't meant for tutorials. Instead, why not create a project and share it in the Show and Tell forum? That way, people can see the scripts you're demonstrating in action, change them easily and remix your project if they want to.