Ivan - it's actually quite simple, though not so simple to describe! Having determined your base exposure (22.6 sec), reduce the exposure setting on the StopClock by 4 steps. That gives you the exposure for the -4 area which is the area receiving the shortest exposure. Now enter Store mode and set +1 step; the total exposure now gives you the exposure for the -3 area. Press the "Compensate" button to tell the StopClock this is a new base exposure (if you don't do this, the StopClock will calculate the next exposure based on the shortest time whereas you want it based on the total time thus far).
Press "Store" and set +2 steps to give you the -1 exposure and press "Compensate" to set a new base as before. Press "Store" and set +1 step, press "Compensate". The total exposure now is back to your original 22.6 sec, and any burn-in times will be calculated from this new base. For example if you now want to burn in each of the four sides of the print by 2 steps, enter a +2 step four times - each will be calculated from the base exposure and all four will be of the same time.
To make the print, expose the whole of the paper for the base exposure time. Mask the -4 area and expose for step 1, mask the -4 and -3 areas and expose for step 2, mask the -4, -3 and -1 areas and expose for step 3. Now mask one edge and expose for step 4 (the first edge burn), and repeat until all four edges are burned in, and you're done.
That hopefully has explained how the base/burn function works. If you don't set a new base each time, subsequent times will be calculated from the original base exposure. Personally I prefer to establish a base exposure for the lightest part of the print and then make a burning-in test strip from there - it avoids me having to think about burning
and dodging. That way I can think of everything as burning-in, which is as much as my ageing brain can cope with these days

.
Some people use percentages instead of f-stops, but then it's easy to make the mistake of thinking a 10% increase and a 10% decrease are equivalent. They're not. 10.0 seconds -10% is 9.0 seconds, but 9.0 seconds +10% is 9.9 seconds, not 10.0. The StopClock does the arithmetic for you, helping you to concentrate on making the print, and once you get used to it you'll find it very easy to use.