Snowball - procedure

[tactac]

Hi! I am doing this app:
http://appinventor.mit.edu/explore/sites/all/files/ai2tutorials/SnowGlobe/SnowGlobeProject.pdf

I have to create a procedure like this one:

However, I cannot do it the same way. I mean, in the procedure it has to appear "ball" but I don't know how. I've done:

Any ideas? Is "ball" a variable? Thank you

[dora_paz]

Click on little gear and drag an input to procedure

[TIMAI2]

Use the mutator (the small blue square) to add an input to your procedure. Change the name of the input to ball

[tactac]

Thank you all for your help!!!!

[TIMAI2]