How to set binding for boots?
 

I have one problem and I need little bit helt with it..
So I have Flow flite 1 bindings, and I don't know how to set their size right for boots, which strap size use, or how adjunst my forward lean, so maybe some one could explain how to set them right, btw my boots size is 11 and on stripes there are sizes, so maybe set size by them, but then in hell there's much free space..
Blah, silly, hope someone will explain how, thank you.