Really, there are two paths. [1] You can either pick one of the preconfigured bags (the names of those bags all start with the letter "B", or "D", or "R" - like the B7 FLIGHT ), or [2] you can pick your own parts and build your own bag.
We put together the preconfigured bags, each one being a different size from very small to very large, because they make a lot of sense for each size, and they are the ones that people were building for themselves more than any others anywhay. They are popular configurations, so at the very least they serve as logical starting points. And in fact, it's likely that one of those will end up being the one you want.
But of course, you could start with the B7 FLIGHT and then swap out one part or another. Like maybe you want the SIDE POCKET ALPHA instead of the SIDE POCKET FOXTROT. Or maybe you'd prefer the PACK CAP REAR instead of the FLAT CAP REAR.
Just add the bag to your Cart and then use The Builder to make any changes you'd like.
Or, you can start from zero by clicking the "Build a Bag" button in the far upper right corner of the home page.