Assuming that you data is in sheet1, columns A, B & C:
1. At the top of each column of data enter the following:
Cell A1: Customer
Cell B1: Year
Cell C1: Balance
2. Click on cell B2. (actually it doesnt matter which cell so long as it is in the table of data).
3. On the Insert Ribbon (just to the right of the Home Ribbon tab), click Pivotable. (on my ribbon its the very left had icon).
4. A dialogue box should appear which has the area of the data indicated in the Table/Range box. Click on OK.
5. At the bottom of the dialogue is the option to choose where you want the table created the default is 'New Worksheet', which is probably best while your trying this out. The other option would allow you to put it where you want, but it might overwrite other cells if there is not enough room.
6. Click on OK. A new sheet will be created with the empty pivotable on the left and a Pivotable field list column on the right.
7. Click and Drag the 'Customer' label (it has a tick box to the left of it, ignore this) to the Row Labels area (bottom left on my screen).
8. Click and Drag the 'Year' label to the Column Labels area.
9. Click and Drag the 'Balance' label to the Values area.
You should now have your completed pivotable. When you update your source data simply right click on the pivotable and choose 'Refresh'
Hope this helps.
Regards