Self employed

The problem is that the 1099-K total is added to my gross sales receipts which already include these credit card sales.  I'm trying to get to the Schedule 1 to manually enter the amount on Part 1, 8z and then again in Part 2, under adjustments to cancel out the amount entered in part 1.  I cannot figure out where in the step-by-step this would be.  I also went to forms & found the line to enter the amount, double clicked on the magnifying glass but it will not allow me to enter anything.  The field is highlighted but it won't let me type an amount.  What am I doing wrong?