Start by choosing what kind of transaction this is — Expense, Income, or Transfer (you can't change this after saving, so pick carefully). Depending on the type, you'll then choose a payment account (where the money's coming from), a receiver account (where it's going, for income and transfers), and, for expenses and income, a category — always a specific subcategory rather than a broad group, since that's what keeps your reports meaningful.
Next, pick a date — it can be in the past, today, or even the future if you're planning ahead — and a status. Most of the time you'll leave this as Completed, meaning it already happened; use Pending if you want to record it now but confirm it later, or Scheduled for something you know is coming but hasn't happened yet.
Enter the amount, and if there's an extra fee attached, add it as a commission — the two get added together automatically into a total so you always know the full cost. If you're transferring between two different currencies, you'll also see a suggested received amount, calculated from the current exchange rate; feel free to adjust it if your bank's own conversion came out slightly different.
If this expense is a payment toward something you owe, flip on Assign to Debt and pick which one (only debts in the same currency will show up). And finally, there's room for a tracking number, a cheque number, and a free-text note if you want to remember any extra detail. If you're entering several transactions in a row, toggle Keep form open after saving so the drawer stays open between each one.