How do I correctly add detergent for heavily soiled laundry?

For heavily soiled laundry, select the programme with Prewash and add one quarter of the recommended detergent amount to compartment I and three quarters to compartment II. Only use liquid detergent for the main wash cycle when using Prewash. You can either place the liquid detergent in a measuring aid in the drum or pour it into compartment II after folding down the liquid detergent insert. (Page 11)