Monthly Accounts spreadsheet help

I am trying setup a spreadsheet to calculate my monthly accounts, so in B3 to B50 named items of income, in C3 to C50 amount’s of income.
In D3 to D50 amount of spending
The in E3 to E50 balance left in account, so I want to show balance in account only where I have entered the details the rest of the columns E4 to E50 shows up as Zero’s until I enter the next entry