You'll need to select the purple function do something block (the first one), then click the blue star on the block. A pop up menu will appear. Click and drag the input block into the block on the right. Then type info. Then click the blue star again. Next, click do something then type printDistance.
If you haven't already -- I'd recommend starting with the vox-l skills and drills section which will show you how to use the Blockly blocks and walk you through some simple mods: https://mod.learntomod.com/badge_pointers/9054 Do the getting started sub section then the learning to program section (which has about 100+ badges)