As in the real world, your club can find a sponsor. A sponsorship can give you extra income each season and who does not want that?
The sponsors have a limited budget to use on sponsorships. They try to obtain the best possible publicity per Credits they invest in sponsorships. The more vifa points your clubs have, the better publicity. The better publicity, the greater sponsor deal.
Club A, which has 1000 vifa points, sends an application of 1000 Credits to Sponsor X. Club B, which has 2000 vifa points, also sends an application for 1000 Credits to Sponsor X. The sponsor chooses Club B's application, because it will get a better publicity per invested Credit.
You can send applications to as many sponsors as you like. A good idea is therefore to apply to one or more sponsors with a very low amount of Credits. This way you can avoid entering next season without a sponsorship. After all, it is better to have a small sponsorship than none. When you have sent a couple of "safe applications", you could send some more greedy ones in order to find your clubs optimal sponsorship requirements.
A sponsorship deal has duration of one season. This means you must apply for a new sponsorships every season.
You can only have one sponsorship at a time. The sponsors will set up sponsorships every Sunday evening. If your club get more than one sponsorship offer the most lucrative of these will be chosen by the system for your club. The sponsorship is paid out immediately after the end of the season.