Brooke,
Here is the basic CTX rotation, it is an entire rotation in itself and can be used alone or in combination with other workouts.
Day 1: Circuit/Back
Day 2: Step & Intervals/Chest
Day 3: All Step/Shoulders
Day 4: Leaner Legs
Day 5: 10-10-10/Triceps
Day 6: Kickbox/Biceps
Day 7: Rest
I don't have the Basic Step/Body Fusion DVD, so maybe someone that does have it can give you more specifics on what sections to use w/ CTX or that can be subbed w/ CTX. However, I would suggest previewing the CTX videos starting to sub in the cardio sections for approx. 30 min. of cardio on the Basic Step portion and then you could "add on a body part" to the Body Fusion section of the DVD. What I mean is that each of the CTX workouts contains an approx. 10 minute upper body weight workout that you could use in addition to that body part being worked in Body Fusion, just select weights that are appropriate for you level (heavy enough that you feel fatigued, almost to muscle failure by the end of the reps, but light enough that you can complete all the reps with good form, this may take some experimenting to find the perfect weight for your level). Just make sure that you don't work the same body part with heavy weights on consecutive days.
From what I do know about the BS/BF DVD you could incorporate it into your rotation, so that you work CTX in more slowly, especially since you are following a beginner rotation, CTX may be short, but it can be very intense!
You could start with a rotation that looks something like this:
Day 1: Body Fusion/CTX Power Circuit Back and Abs
Day 2: Step & Intervals/ CTX Chest
Day 3: Body Fusion Cardio/10 minute Core Conditioning from BS/BF
Day 4: Leaner Legs (Make sure to start with a Light Barbell or dumbbells if you are new to weight work, or even use no weights at all at first, you'll still feel it!) Skip the abs this time around
Day 5: 10-10-10 (Do the kickboxing and hi/lo sections only, then sub in combo 2 from the Basic Step DVD)/ CTX Triceps/Today do the Abs from Leaner Legs
Day 6: CTX Kickbox/ CTX Biceps(skip the abs)
Day 7: Rest
Then you could also mix it up like this:
Day 1: Power Circuit
Day 2: Basic Step
Day 3: Body Fusion Cardio segments only/Any abs segment from CTX
Day 4: CTX All Step Cardio/BS/BF Lower Body Conditioning
Day 5: Step and Intervals Cardio/BS/BF Upper Body Conditioning
Day 6: Kickbox Cardio and Abs (skip biceps)
Day 7: Rest
HTH! Have fun!
Mattea