Please Help me i need VBA code for this

Sheet 1 Data
________________________________________
A B
P.Code Balance Amount
1 100 25000
2 101 1300
3 102 7800
________________________________________

Sheet 2
I have Detailed Bills

A B C

P.Code Bill No. Billwise Details

1 100 A123 1000
2 100 A124 15000
3 100 A125 5000
4 100 A126 8000
5 101 ABC 500
6 101 ABC1 800
7 101 ABC2 500
8 102 Z123 2000
9 102 Z124 800
10 102 Z125 2000
11 102 Z 126 3000
12 102 Z1276 2500


OUT LIKE THIS.............................

A B
C D

P.Code Bill No. Billwise Details ACTULS
OUTSTANDING

1 100 A123
1000 0
2 100 A124
15000 12000
3 100 A125
5000 5000
4 100 A126
8000 8000
5 101 ABC
500 0
6 101 ABC1
800 800
7 101 ABC2
500 500
8 102 Z123
2000 0
9 102 Z124
800 300
10 102 Z125
2000 2000
11 102 Z 126
3000 3000
12 102 Z 1276
2500 2500



Column D is Actuls Outstading of my Bills this should be Sheet 1
P. code amount Equals .


P.CODE= 100 Balance is Only 25000 But we have Bill wise details
More than Rs. 25000 . we need Last in first out method Bills only

P.CODE = 101 Balance is only 1300 But we have Sheet 2 Data is
more than 1800 so we need only 1300 down up Bills details only

like this only will come but i dont know code how i start any
one help

Chandru