I'll try and help you out with working through the spreadsheet then as it can be a bit confusing the first time you look at it.
All the yellow cells on the spread sheet are inputs and can be changed, green cells can not be changed.
On the top let hand side you can see it ask for diff ratio, tyre height & Revs/km. Diff ratio should be pretty straight forward to work out and as for the tyre information there are tyre calculators online where you just put in your tyre size eg 285/30/20 and it'll give you revs/km and tyre height.
Once all that is filled out you can move across and there is 3 sets of 3 tables, each table at the top of each column is again yellow which means you can change these figures and the 2 tables below are green which can not be changed. The first column top table is labelled OSS rpm, so you can copy the shift pattern straight out of your tune file and paste it here. Once you've done that you should see shift speed and engine rpm tables change which will show you with that diff ratio, tyre height etc etc and those OSS values it'll shift at this speed and this rpm. For example 1st to 2nd in the below screen shot at 98% TPS with OSS value of 1125 the car will shift at 52km/hr and the engine rpm will be 4691. Be mindful it might not be exactly that but it'll be pretty damn close to that, like I said this will get you in the ball park.
Same principle works for the next two columns. Second column of tables is for shift speed, so say you want the car to change gears at 50km/hr 1st to 2nd at 98%TPS than you put 50 into that cell and it'll change the OSS RPM and engine rpm tables so you know what OSS value you need to put into your shift table on your tune for it to change at that given speed.
Finally the last column of tables is probably the table your looking for as you can input the engine rpm you would like the car to shift at and it'll give you the speed and OSS, put this OSS into your shift pattern table on your tune and it should shift close to the engine rpm you inputted into the top table
Hopefully that helps you out a little bit, after reading it back a few times I'm not sure if it'll confuse you more or help you out.