Chest Voice

In the lower range I do not have the power I have in my upper range what can I do to impprove this?

Hi, Dianne! I'd first pay attention to your technique in 3 areas: (1) breath support, (2) cord closure, and (3) resonant space. Since you mentioned that you do have power in your upper range, I recommend you take note of what you're doing right to achieve that power, and notice if anything changes within your technique when you get into your low/chest register. My guess is that those notes need more breath support, firmer cord closure, or an adjustment in resonant space. 

To train all three, use the syllable "GUH" on any chest voice exercise, to help you feel some air pressure build in your abdomen and initiate the sound with your cords together (on the "G" sound). If you've spent a lot of time strengthening head voice, it's likely that your chest voice function is just not as strong yet! Commit to exercising chest voice daily, even if there's a disparity in sound & strength for the time being, and let me know how it's going for you.