Scratch

does anyone here know how to make a platform game?
i'm trying to make one.
the zeke's sword video game is coming out on scratch
and there is a lot of variables and stuff here's a sneek peek you can tell a lot
just by the scripts

<when green flag clicked><set size to(100  )%><show><wait( 0.5 )secsc>
<play sound[ music ]and waits><change{ charge }by( 1<if>right arrow key pressed

<when[left arrow ]key pressed>chang charge by 1

i just need help with the jumping part