extrude operation in cst

in this video how to use extrude operation in CST has been expained.

[@daryenplays4148]

How you select backside of substrate... What button you click

[@nagalakshmi6436]

if u press number 3 back side of substrate will come

[@ptolemeausd8173]

how about appling substraction

[@ULearnEasily]

in modelling tab boolean subtract function is there