How to compare two columns in two worksheets

Hello,
i need a macro code that can compare two columns in two excel files as :


File1 File 2
A B A B
1 ID stock 1 ID stock
2 AB-C1 5 2 AB-C1 2
3 AB-C2 100 3 AB-C2 1
4 AB-C3 3 4 AB-C3 3
5 AB-C4 1 5 AB-C4 1
6 AB-C5 6 6 AB-C5 6
7 AB-C6 9 7 AB-C6 9
8 AB-C7 3 8 AB-C7 5
9 T-001 55 9 T-001 0
10 T-002 66 10 T-002 1
11 T-003 77 11 T-003 22
12 T-004 21 12 T-004 1
13 T-005 69 13 T-005 9
14 T-006 10 14 T-006 15
15 T-007 3
what i need to do is to compare columns A in file2 with column A in file1, if its do exist then replace the data of column B in file1 by the data in column B in file2 at the same row, example: AB-C1 in file2 do exist in file1 so put the data in cell B2 which its number (2), in cell B2 in file1 instead of number (5) and then color the cell A2 in any color lets say red, and so on.. P.S : not necessary the new results must be in file1, we can put it in new file or new sheet.
please help me as soon as u can.
and thank u.