The pattern given is of a half-boned pair of stays of the 1760s/1770s. It has been developed by draping, following a pattern from Waugh's Corsets and Crinolines. Its simplicity makes it most attractive for the beginner. If you want a pattern for a different decade, the book contains many more, I also have patterns from Diderot (3rd quarter of the century) online, and of course there are companies that specialise in period patterns - see purveyors page. The following instructions are for the given pattern only, but if you're advanced enough to try something more sophisticated, you should be able to adopt them easily. Chapter 5 also looks at stapless, fully-boned, 5-panel stays. The pattern here is meant for a person of approximately 82-90 cm waist and 100-110 cm bust, natural measurements. Seam allowances are not included.
There's an extra chapter about resizing the pattern for other measurements. Remember that there should be a gap of a couple of centimetres where the lacing is, so minor adjustments can be done by lacing more or less tightly.
The inner, straight lines of the pattern represent the boning. It should go through into the tabs as far as you can make it. The waistline would painfully dig into your waist if the boning ended there. It is not necessary to follow the placement exactly as in the pattern. The most important bones are the most slanted ones in each pattern piece. The rest can be placed to taste, fanning out between side seam and diagonal bone, and between centre front/back and diagonal bone. The number of bones you can fit into that space depends on the size of the bones and of the stays. The bone that runs diagonally across the other ones in the back part can and should be left out for simplicity. I just forgot to delete it from the pattern.*
I have also left out the tab slits, except for the ones closest to the centre front and back. You should determine the placement of the other slits in accordance with the boning placement in such a way that as many bones as possible continue into the tabs as far as possible. Unfortunately, the slits are supposed to meet the waistline in a roughly 90° angle, while the bones arrive at a sharp angle. It may not be possible to have a bone in every tab, but try at least in the tabs closest to the sides. Have a look at this picture of one of my projects to see how the bones (that's the wide strips) run into the tabs.
All slits end at the waist line of the pattern, which is represented by a curved line. It sits at your natural waist at the side seam and then curves down towards the centre front/back.
I have left out the shoulder straps as they are easy to cut and their length, positioning, angle etc depends greatly on the shape of your shoulders and whether you want them close to the neck or away from it (the latter is safer in case you'll ever make a dress with a wider neckline). It's all a matter of fitting. Cut them as wide as that part of the back to which they attach (that's the slanted, straight line running from point [8; 43.5] to [15;40]) at one end, then tapering to about 2-3 cm wide with a slight curve to the neck-side edge, and 30-40 cm long, like this. Make the straps from as many layers as the body.
If you want strapless stays, it is not enough to simply leave the straps off. The top edge of both back and front must be altered to look like in the pattern in chapter 5.
Chapter 3: Cutting and making up
*) Actually, the original pattern also had bones running roughly parallel to the bust line. The reason I recommend to ignore them for the moment is (a) that they're not really necessary, and (b) their tunnels would have to cross the other tunnels. You'd have to know exactly where the tunnels cross, remember to leave gaps in the tunnel seams at the crossings, and any number of other complications I wouldn't want to sick on a beginner. If you really, really, really want to know how it's done, ask me.