Once you've won your election it's time to start negotiating a contract! The employer is obligated by law to negotiate over all items that are directly related to work, such as safety, wages, benefits, discrimination, seniority, scheduling, and more.
But the organizing is not done! Winning a good contract requires having built enough power to force the boss to make concessions.
Negotiating a contract requires a lot of planning, strategy, and participation from coworkers so that you can win the best possible work conditions for you and your peers. Recruit a representative bargaining committee and be ready to conduct many actions in support of your negotiation demands until you win an agreement.
A contract by itself is not the end goal of a union campaign. The goal is to build power. A contract can help capture certain concessions from the boss, but if it's negotiated without the full backing of all your coworkers then that contract will be more symbolic than substantive.
All of this means that the organizing never stops. A union is a vehicle for increasing workers power, and that means you and your coworkers must always be communicating and organizing so that you're ready to take action and fight the boss whenever necessary- with a contract or without one.