Being a layperson of the Machine Cult puts you in a weird sort of half-status between the usual techno-ignorance of a Imperial citizen and actual understanding of technology that comes with Mechanicus training. Darkling's suggestions for playing a Machine Cultist aren't wrong, those are the sort of behaviors a forge world native would probably exhibit; but you do have slightly more understanding of technology than average - Technical Knock and Common Lore (Tech), from being around technology all your life to where you picked up some useful stuff just by osmosis. It's still steeped in prayer and ritual, but being raised in the Omnissian faith teaches you the prayers and rituals that actually<em>work</em>for common devices.