Convert Formulas into VBA

How can I convert the following formulas into VBA?
=IF(ISBLANK(C2),"",VLOOKUP(C2,Inventory!$A$2:D37812,3,FALSE))
=IF(ISBLANK(C2),"",VLOOKUP(C2,Inventory!$A$2:D37812,4,FALSE))
=IF(ISBLANK(C2),"",VLOOKUP(C2,Inventory!$A$2:D37812,2,FALSE))
=IF(C3="","",A2)
Each one needs to go down the entire range of rows. Sample spreadsheet is attached.