To create a petty cash within the sidebar open the Bookkeeping->Bank Accounts page. At the top right corner click Add bank account .
Within the bank listing view click the Add without bank feed button.
Here you can now enter your petty cash account.
Enter a bank name such as Petty Cash. For the account type feel free to also enter Petty Cash. Important for the account name is that it's a unique account name.
For the account type select now Cash in hand.
