How do I get to the code to load/function

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C#

I have downloaded code to DOWNLOADS
I unzipped the code only to see a folder soduko
so I inspected folder to see a further folder called soduko
I opened this folder, to see a sln file

tried to use this Sudoku.sln file
it opened up VS2019 to give me message that files were missing

C:\Users\thesh\AppData\Local\Temp\Temp3_Sudoku.zip\Sudoku\Sudoku\Sudoku\Sudoku.csproj : error  : The project file could not be loaded. Could not find a part of the path 'C:\Users\thesh\AppData\Local\Temp\Temp3_Sudoku.zip\Sudoku\Sudoku\Sudoku\Sudoku.csproj'.  C:\Users\thesh\AppData\Local\Temp\Temp3_Sudoku.zip\Sudoku\Sudoku\Sudoku\Sudoku.csproj

Help is Urgently requested, what should I do / not have done

I wish to run your code, understand it, and hopefully add to it !

please treat me as a rank novice !

thankyou in advance

What I have tried:

as above the detail steps above