I am completely new to VBA, and need to make a macro in an empty workbook.

I need to sum up the data in the column J from workbook1 sheet1 (workbook titled CA), column I from workbook2 sheet1 (workbook titled NE), and column G from workbook3 sheet1 (workbook titled SI).
IF data from column C from workbook1, column C from workbook2, and column D from workbook3 match.

This is to sum up available stock if SKU numbers match. Could anyone assist me with this issue?