In order to show a movie in your theater, you would have to get in contact with the local distributor. There will be plenty of them in your local area, you should find them out and contact them. You can also take help of the other theater owners and enquire them about distributors. Feel free to take suggestions from other owners and contact the referred distributors as soon as possible. Beware of the unlicensed distributors, you should not do business with them.
Choose a distributor according to your feasibility and set your terms and conditions with him. If your business is new, then know that the percentage deal can be good for you, as you will be only paying a portion of your earnings instead of a predetermined fee before the start of the show.
You should sign a formal agreement with the distributor to avoid any unpleasant experience in future. After a few months experience, you will be able to decide what is better for you, fixed price or a percentage.