For three seasons Lisa Kudrow, 47, has dispensed horrible advice under the guise of self-absorbed therapist Fiona Wallice in the award-winning online improv series Web Therapy (lstudio.com). And starting July 19, the dark comedy comes to Showtime in a 30-minute format, using therapy sessions from the Web version's first two seasons mixed with new segments about Fiona's personal life. ''We thought, 'Let's not just string our webisodes together,''' says Kudrow. '''Let's see if we can work in more of the narrative.''' This fleshed-out version includes more airtime for Victor Garber, who plays Fiona's husband, Kip, as well as new cast member Lily Tomlin, who stars as Fiona's callous mom. ''With her mother, you understand a little more,'' explains Kudrow. ''[She's] the only person who can shut Fiona up. It was fun to improvise with Lily, who was so perfectly this character. I've never spoken less.''