How do I Run a query on Journal Entries so that i can find out all the expenses I have done so far?

This is an incorrect approach to finding out what you want for two reasons:

  1. Most expenses will not have been entered via journal entries. Most will have been entered by spending money from a bank or cash account.
  2. Expense totals by account are visible upon program launch on the Summary page. If the time period does not include everything you want to see, modify it via the Set Period button at the top.