There are sample files in the Bank Reconciliation sample data. The files are different for Payments and Deposits and must be imported separately.They are in comma separated format (CSV).

CSV file for Payments = \Softrak\BRWIN\SAMDATA\BRPAYIM.csv
CSV file for Deposits = \Softrak\BRWIN\SAMDATA\BRDEPIM.csv

The best approach is to first test in sample data so that you can see what the Import template must look like.