Welcome. I noticed that you posted something similar in the YNAB Pro forum, so I'm not sure if you've got Basic or not, but I'll go forward as if you do.
I think that you're using some terms differently than intended. There are three tabs at the bottom of the screen.
The two initial steps would have been to set up your accounts (checking, saving, cash, etc.) on the
Overview Worksheet and, make any desired changes to the categories provided on the
Budget Worksheet. The changes you make there to the categories will automatically carry over to the category list on the Overview Worksheet.
To get money into your budget initially, you do that via the
Register Worksheet. You mention August briefly, but then focus on September, so I'll assume that you entered things in August to begin September first. In the register in August you should have entered your account balances for each account using the category of Primary Income (again, assuming that you entered them in August to budget in September) as inflows. This is the same place that you should have entered each transaction as you spent money, as outflows.
Once you have your money available as described above, then you go back to the Budget Worksheet to budget your money to zero in the Budgeted column. When you enter transactions on the Register Worksheet, then those amounts will show up in the Spent column.
I'm not sure if you inadvertently used the wrong terms or are trying to use the program in a way other than what it's intended. Here is a link to the Basic tutorial. If you've still got questions, post back.
http://www.youneedabudget.com/tutorials ... AB%20Basic