A credit card linked to the bank account of your company does not need to be reimbursed to you. Therefor the administrator of the company account will create and manage these payment methods for you.
All personal (reimbursable) payment methods you want to add on top of this, you can create via 'Settings' - 'Payment methods', by clicking on the green button 'Add payment method'.
'Cash' is added already by default for each user.
By clicking on a payment method the detail will open, where you can also indicate it as your default payment method for all expenses. This means that payment method is always automatically filled in for you - but still changeable of course, whenever needed.
You can deactivate a payment method when it is no longer relevant, so that it does not appear in your payment options anymore when adding new expenses. To do so you just open the payment and uncheck the box before 'Activate'.