I sympathize completely. Heller sailing ships are notorious for beautifully-rendered decorative elements, inconsistent accuracy, and hopeless instructions.
There are plenty of good books that introduce the subject of rigging. The problem is that most of the ones in English concentrate on British and American practice. The French did most things about the same, but there are differences - and I'm no expert in them.
Two books that do cross the national boundaries are Historic Ship Models, by Wolfram zu Mondfeld, and Eighteenth-Century Rigs and Rigging, by Karl Heinz Marquardt. The Mondfeld book is fairly widely available in paperback, and reasonably priced. It covers an enormous amount of material - none of it, unfortunately, in much detail. The Marquardt book is quite detailed and beautifully illustrated, but also quite expensive.
The best expert on French sailing ships in print is a superb draftsman and researcher named Jean Boudriot. He published a large number of volumes dealing with specific vessels, including one on the frigate La Belle Poule of 1769. I'm not sure whether that's the same ship the Heller kit represents. If so, that book can be taken as the definitive resource on the subject and will tell you more about the ship than you ever wanted to know. Unfortunately Boudriot's books are hard to find and hideously expensive. If you live in the vicinity of a good research library, though, you might be able to find them there.
Some good sources on the British side are readily available. A good, cheap contemporary one is Darcy Lever's The Young Officer's Sheet Anchor. It dates from very late eighteenth century, but later editions got updated. Oddly enough the Lee Valley woodworking supply company (<www.leevalley.com>) publishes a nice, very reasonably priced edition of Lever, with updates that cover the first half of the nineteenth century.
An encyclopedic reference book on rigging (but again with a British slant) is James Lees's The Masting and Rigging of British Warships. That's a basic reference that's in the libraries of most serious sailing ship modelers.
The Musee de la Marine in Paris publishes a series of plans of famous French sailing ships. I think La Belle Poule may be among them; I'm not sure. If so, the plans can be obtained through Taubman Plan Service. That's a mind-boggling source for ship plans, operated by an octegenarian gentleman who's one of the hobby's great celebrities. He does have a website, but it isn't complete. To get his full line of plans you need to order his printed catalog (otherwise known as The Ship Modeler's Wishbook), which costs $10.00 (including postage). The address is Taubman Plans Service International, 11 College Drive, Jersey City, NJ 07305.
If you can handle only one book, the Mondfeld one probably is the one to start with.
Those are the ideas that come to mind immediately. Hope this helps a little. Good luck. It's a great hobby.