First thing to do is go back to Lowes and get another Juniper...LOL!
JK...I did the same thing on my first, only I actually cut even more than you did! It was a four branch with a little poof at the end. I named it Fugly.
You don't need to remove everything close to the trunk, just open it up so you can see the trunk line from the "front" of your tree.
Honestly, as your first Bonsai, your probably not going to win any awards with it, so do what I did... pot it up in a suitable pot (in spring) and learn to keep it alive!
In the meantime, read - reAD - READ! Read about styling and wiring and pots and soil wars. Look at lots of pictures of great bonsai by great bonsai masters. Join a bonsai club, visit a bonsai nursery, maybe take one of their classes.
Better to learn on this $7 nursery Juniper than one you paid several hundred dollars for!
I managed to keep Fugly alive for 3 years, until August 2016, when I had to undergo two surgeries. Fugly just wasn't that important at that time, and died from neglect. Everything worked out OK with the operations, but I wish I still had Fugly around.