I used to open an advertising shop and make banners for business card publicity pages. How can I contact the printing factory? What equipment do you need in the store and who do you need to recruit?

It depends on where you come from and what kind of advertising you are going to do. There are too many advertisements, such as printed matter, cards, spray-painted photos, luminous words, crystal word, and a series of them. It will take you some time to get familiar with these, let alone do them. You can only learn by doing. There are so many manufacturers to supply that you can't find them all at once.