The advice I'll give is based on my experience as cofounder of an early online banking technology company back in the mid-90s. We started with three people in rented class-C space and over seven years did high six-figure deals with large and small banks including Fleet, Bank of America, Citi and others.
There's not really a "how it works" for this. If I had to tell you how it works I'd say: it works by you making friends inside a corporation and convincing them to buy your product. Did that help? :). Probably not, so here's a little more: you preferably start with a member of your founding team who is articulate, outgoing, amiable and enjoys meeting and talking with people. That person needs to know the product and competitive environment cold, and it helps if they are passionate believers in the value prop. They need to have an identified list of target companies. They need to start calling and emailing and working contacts to get meetings. Eventually, if you actually have a value prop, one of those meetings will result in a relationship with someone who is willing to champion the product internally.
You then work outward from that contact, meeting with their colleagues, eventually identifying decision makers who control actual budget that can be used to pay you for something. If you do all this skillfully then you may get them to commit to a purchase. They will then have to shepherd you through a potentially long series of internal policy and legal hurdles. You may need to get on a qualified vendor list, or meet certain business stability criteria. You will likely need approvals of the deal from different departments, and their legal team will review and try to negotiate any agreements you request them to sign. You can see why developing internal champions is absolutely critical. In every single successful deal we did, by the time we got to the second or third round of meetings our internal champions were doing most of the selling.
The last thing I'll say is that it can be powerfully tempting to think you can purchase success at this by hiring the right magic person who can work their little black book and make sales happen. I tend to doubt it, and it definitely never worked for us. A founding sales person can make this happen. That's the person I'm talking about above. But just bringing in a hired gun is unlikely to result in success imo. I think you need to believe in your own thing enough, and be good enough at talking about it, that you can land your first few deals. Then when you do bring aboard professional sales people you'll have some actual idea of why people buy from you and how to systematize the approach. Good luck with it!