Hi
Follow these steps:
1. Click on the grey box in the top left corner of the worksheet between the 1 and A to select the whole worksheet.
2. Right click anywhere on the sheet and choose Format Cells then click on the Protection tab.
3. Unselect the Locked tick box and click OK.
4. Click on the header of the column you want protecting to highlight the column.
5. Right click anywhere in the highlighted column and select Format Cells then click on the Protection tab.
6. Click in the Locked box to put a tick in it and select OK.
7. Click on the Review tab and select Protect Sheet.
8. You have the option to enter a password to protect the sheet.
9. Enter a password if you wish and click OK.
Your column will now be protected from changes.
Good luck.

Tony