Once upon a time getting a “blowout’’ was, well, cut and dry. When hair stylist Alli Webb launched Drybar in 2010, she gave women all sorts of fun, fast, and affordable options, such as the Straight Up (straight with a bit of body), the Mai Tai (effortlessly beachy), and the Southern Comfort (all about volume). To supplement the 60-plus Drybar locations, Webb has just published her first book chockfull of at-home hairstyling tips. Webb will be in town to sign books Oct. 22, 11 a.m. to 3 p.m. at Sephora in The Shops at Prudential Center, Boston. “The Drybar Guide to Good Hair for All: How to Get the Perfect Blowout at Home,’’ $24.95, available at Sephora during the signing and at all Drybar locations.