Confused Cadian Shock Trooper

Notes:

"Yes, I called this guys "Cadian Shock Trooper" and NOT an "Imperial Guard", you are free to shoot me in the face for heresy. ;)"

P.S – Hey everyone, who read this, svolozhanin7 here. I'm new to 40k franchise, never read any book/lore about it nor I played any games. Can you give me some tips on where should I start?

Meme by me.