To check your luggage allowance and seat assignment, go to the Trips page and open your trip. You can see the luggage and seat information on the left next to the flight details. 

If there are multiple travelers on the relevant flight, click See details. You'll find the luggage and seat information for each passenger underneath the flight details.   

If you need to make any changes to your luggage allowance or seat allocation, follow the instructions to Manage luggage and seats for booked flights.