No need to think the budget template is only for one month. Just keep typing the date in the date column of the "Transactions" sheet and the details will update. You should adjust the budget categories to match the duration of time you want to use.
If you do want month-by-month, then you can switch to the "Transactions" sheet, select the table, cut
then switch back to the "Budget" sheet, paste.
Now rename the "Budget" sheet something like "Budget Jan 2014", and delete the "Transactions" sheet. Set the budget for Jan in the column I highlighted above. The subsequent months, duplicate the monthly budget:
Then adjust the the entries in the transactions table inside this sheet.