Possibly with some very long wires. ; )
Kidding aside, you provide some kind of information sharing capability between HO and your branch offices. It may be comprised of wire, fiber, radio or even some combination of those. Physically, your sharing provides paths so that information, somehow, can be passed between all your sites. What the path structure looks like, we call a topology, and might be everything from a "daisy chain", (think of a physical chain, where each site is a chain link), to a "full mesh", where each site has a direct path to every other site, to many other combinations of how your sites interconnect (NB: physically, again, media might be wire, fiber, radio or some combination, from all paths being alike, to each being different).
Once you have a way to convey information, we get into higher levels of network design, such as routing and even higher considerations.
Many, many different ways and approaches when developing network solutions, some more suitable than others, depending on other factors.
If this is beginning to sound just a bit complex, it can be, which is why "expert" level network engineers often have years of study and even more years of experience.
Assuming you're not a network engineer (by your question), possible you should consider retaining a network engineer to design and/or setup your HO and branch connections. (NB: like many other professions, you can hire such, or retain one, or more, by contract. [For the latter, if you already have someone that supports PCs/Servers, the "hard stuff" might be provided by a network engineer, by contract, with your existing support person shown what to do to "maintain" the network.])
