Filling Excel file using DataTable


I have built DataTable with 123 columns and i have about 250 excel files which are in their own subfolder and last 3 characters in file are same as the column names in my DT. Firstly I do some activities for each that excel file and when I am done i want to add that file name to the column in my DataTable, currently i am using IF(last 3 characters of file=column name)->add data row and i get results but not good enough. Every time my loop adds new row and it doesnt look nice (look at the picture, data in cells is only for example)

So I want “BBBB” to be just under “AAAA” and that “CCCC” is in first row of “005” column , also I want that columns that are empty like “002” to stay there because later i need to recognize which columns are empty.