Correct. Make sure your starting balance is a negative number when you started the account. You can adjust this by selecting your account, then go to the account menu at the top of the screen and select 'Edit Account...' This should bring you to the screen where you can adjust your starting balance again.
When you make entries in a debt account, like a purchase, interest or fees, make sure you are adding them as debits. The amounts will automatically be negative and will add to your debt. In your example -200 will become -250. When you make payments towards your credit card, those need to be made as deposits. These amounts will lessen your debt. The ideal is to get that credit card balance to zero and keep it there
I hope this helps!