Traffic can be generated in two ways: organically, or by advertising.
Organic traffic is that sent to your portal via the search engines, which will occur once your website has relevant keywords and images that search engines can suggest to any user who searches for them.
The more content you have on your portal, the greater the reach you will achieve.
Having businesses write their keywords and tags on their pages, increases their chance of appearing on the search engines under your name.
Including info about your city, landmarks, tourist attractions, also gives your portal greater keyword diversity.
Paid advertisement on social media and search engine platforms is also an option. Such platforms allow you to select the audience that will view your adverts, reducing the chance of having uninterested people see your sponsored ad.
Specialized social media groups offer a great place to spread the word about your platform.