Congratulations on finishing the book! By now you should be an excellent guitar player, and be getting a lot of pleasure from playing your instrument. Try to play with other musicians as much as possible, as this will help to develop your playing and also put your licks into a musical context. Make a habit of improvising your own licks and solos, as well as trying out any of the licks in this book.
If you wish to move on to more advanced playing in specific styles, there are several more Progressive Complete Learn to Play Guitar Manuals covering Lead Guitar, Rhythm Guitar, Blues Guitar, Rock Guitar, Jazz Guitar, Fingerpicking Guitar and Classical Guitar. All are highly recommended.