If you want to look for transactions within a date range, you probably want to run a Report to do so. Gnucash seems to be organized around the concept of using the registers primarily for entry (although they do have some filtering and search capabilities), but to use a Report when you want to see information or get an export for tax documentation purposes.
I would recommend looking at the documentation on Reports, and particularly try out the Transaction Report to see a list of transactions for a particular date range. That's what I use to export a list of transactions to put totals on my tax returns.
You may also want to look at setting your accounting period, if it doesn't follow a typical calendar year.