Ratings Model - Unable to change from one rating to the next

Hello.

I initially posted this in general excel forum (sorry! any mods might want to remove it from there).

My issue is more to do with formulas, with which I am still very much a beginner. Any help for the below would be much appreciated.

I am trying to solve the attached issue spread over two excel sheets/tabs.

I have worked out the rating of each person's chances of winning (SHEET 1) and I now want to make this more automated so I can enter ratings and the data will automatically update with the expected chances of that person winning (SHEET 2)

I have worked out that a person rated as '1' has an expected chance of winning against any person rated 1,2,3,4,5 and so on... and i can enter in different ratings of the opponent and it calculates fine.

How do I create a spreadsheet that will allow me to enter someone rated '2' or '3' and their expected chances, or simply change the rating of the player and have the spreadsheet update.

I want to be able to change the ratings at any time and have the spreadsheet replicate this.