Scania R420 opticruise gearbox question

May have to drive one soon. Had a look at one the other day but can anyone give me a brief idea how the column selector works?
Maybe a daft question but here goes …
Do you just put it on D to drive? What is the clutch for if it’s automatic? Is that for if you use it in manual? What is H for?

Thanks for any help folks

its a semi auto, you use the clutch as normal to set off with and stop and also to go backwards with apart from that you dont touch the pedal, takes a little to get used to but jsut set of and stop with the clutch peddal,
H… is for hill climb, it gives you a few more rpms and holds the gear a little longer before changing, they are ok for a semi auto a little slow some times changing but i liked the one i had after i got used to not pressing the clutch etc, hope that helps ya, daz
press pedal then select D… then let peddal out as normal, same for reverse peddal down then select R, dont rush them in switching between the d and r either,