Watch the More Open Chords online guitar lesson by Bruce Arnold from Jazz Guitar for Beginners
Adding 7ths to chords can give them a fuller, richer sound. Which 7ths to add can be confusing to a beginning guitarist. Doing the recommended theory work will help you to know how to change a chord progression on your own.
You should learn all 7th chords. (I would recommend Chord Workbook for Guitar Volume One and Two, These two books provide all 7th chords commonly used by professional jazz guitarists.)
The jam tracks for the chord progressions get progressively faster so skip ahead if you would like more of a challenge. You can also practice the chord progression with a midi file.
This will allow you to set the tempo, find the one that initially works for you and gradually speed it up over time.