Small C# program to Compare CSV.

I need a small program to compare a CSV file with an excel spreadsheet. The program has to be written in C# VS2017. The user function Via a file dialog, the user selects the master excel file and a file dialog to select the CSV file and then press a button "Compare". Then the software loads the excel file and selects automatically the sheet with the name "PLC io liste". In the sheet the program as to use 6 columns and compare these data the CSV file 6 columns. The sequence of the program needs to be like. 1. Load the two files 2. Start compare 3. Only look in the CSV file where the data "column1" is like the data in column name "Class" in the excel spreadsheet are equal. 4. Then the compare function starts to look in the column name "Class" from the excel spreadsheet if the data exist in the CSV file "column2". If there is a match then the program needs to check if CSV column4,5,7,8 are equal with the column name "MIT-Addr.", column name "Type", column name "Comment" and column name "Remark" from the excel spreadsheet if so then everything is good if not the program has to show in a data grid view where there is a difference. 5. If there is no match in point 4 then it also has to be shown in a data grid view. The sample files are only small files the real ones can be up to 200 MB each.