Pick your bases, your on-duty days, the trips you like and the aircraft you want. Lines are awarded in seniority order once bidding closes.
Trips are fixed route chains flown over several duty days. If you're awarded one, its legs drop onto the on-duty days you selected above — in order, starting from your first — so it runs back-to-back if you picked consecutive days, or with rest days in between if you didn't. Flying it to completion earns a bonus. Your list order is your preference order.