I am new to rebounding and really enjoy it but I feel it in my lower back. I am wondering what I should be doing differently so I can continue to do the classes.

Hi Theresa,
If you are able to jump on a bungee trampoline with more give in the bounce this may help. Flat feet, core engaged, pressing into the mat, go lower not higher. Begin by not lifting your feet at first, so you cam get the feel of the core engagement.