To create the Customer import file from the provided ICUST.xls file, do the following steps.
1. Open the ICUST.XLS file and the file you intend to copy from. Make sure you do not delete or change the name of any of the columns in the ICUST.XLS file.
2. Copy from the excel sheet you are copying from, and paste it into the matching column on the ICUST.XLS file.
3. Once all of the data has been copied & pasted, save the ICUST.XLS file (do not change the name). Make sure the save as type is EXCEL 5.0/95
Below is a video explaining in a bit more detail how this process works.