Add a column based on cell value

[sweeper2311]

I need to add a new blank column to the right of an existing column based on the value in row 3 of the existing column. As in if C3=Outside Vendor add a column (will become column D) but if its anything else don't do anything. Ideally if I could copy format from the existing column it would be ideal but I can always reformat if need be. If i can do it without VBA would be ideal as I know virtually nothing about VBA. Current spreadsheet runs column A:BLF. I'll be adding a new column beginning between F:G and will be after every 4th one after that (J:K before the addition between F:G would be the second one)