Oooo Marvy! Now here's a book for all you divine creatures out there. Why be a stay-at-home when you can play at home. . . or anywhere. And ""anyone can do it"" says San Francisco's answer to Truman Capote. After all, little Patsy Lou came from nowhere Oklahoma and now look television, radio, personal appearances, charity ball consultant who has bashed Frank Sinatra and just keeps the social swirl in a mad uproar by throwing little soirees like that just ultimate groovy Mod party a year ago. Of course it helps to have been a model (just try stuffing a dumpy you into a sleek hostess gown). And it also helps to be a blithe spirit--one major point--don't worry about money. And Miss Montandon obviously doesn't, there always seem to be some provident ""beaus"" handy. Or ""Party Buddies,"" ideally a male neuter. But if you have that urge, this how-to expertise includes everything but alka-seltzer. From making up the guest list--lots of young, a dash of old, a sprinkle of extroverts, an exhibitionist or two, don't forget some good listeners, etc., to menus, types of have-a-balls--Mexican fiestas, etc. to ladies' luncheons to picnics and on and on. Miss Montandon even outfits you with a diet, personal make-up checklist and exercise chart to get you in the mood. No party poopers please.