Hi Tina,
Working with your first unmounted stamps can be kind of scary or intimidating when you're only used to wood mounted, but once you get used to them you'll love them! There are a few different ways to use your Bella stamps, depending on how you want to store them. Knowing that you're used to wood mounted stamps that have a cushion, I'd probably recommend that you try EZ mount on one of your stamps and see how you like it.
EZ mount is just like the gray foam that is in between your rubber stamps and the block on your wood mounts, except it is sticky on one side and has a cling surface on the other side. Here is a step by step guide from the people who make EZ Mount:
Instructions.
After I got used to unmounted stamps, I use most of them without cushion with either Tack N Peel (makes your acrylic block sticky so the stamp sticks to it) or double sided tape. But since I was used to wood mounts, it took a bit of getting used to. I was happier with the results from mounting with EZ Mount as a transition from wood to unmounted rubber.
Hope this helps!