To select your seat on Spirit Airlines, you can follow these steps:

1. **Visit the Spirit Airlines website**: Go to the official website of Spirit Airlines: [Spirit.com](https://www.spirit.com/).

2. **Log in or Retrieve Your Booking**: If you haven't already logged in, you'll need to do so. If you have an existing booking, log in using your confirmation code (also known as the PNR) and your last name to access your reservation.

3. **Access Your Reservation**: Once logged in, locate and access your reservation. This should be on the homepage or under the "My Trips" or "Manage Trip" section.

4. **Choose Your Seat**: Look for the option to select your seat. Spirit Airlines typically offers seat selection for an additional fee. You will likely see a seating chart with available seats highlighted. Choose the seat you prefer, considering factors like legroom, proximity to the restroom, window or aisle preference, etc.

5. **Pay for Your Seat Selection**: After choosing your seat, you'll need to pay for it if there's a fee associated. Follow the prompts to complete the payment process.

6. **Confirmation**: Once you've selected and paid for your seat, you should receive a confirmation either via email or within your Spirit Airlines account.

If you encounter any issues or have specific questions about seat selection, you can always contact Spirit Airlines customer service for assistance.