ok first off just because your in a gym with lots of padding etc
does not mean you are invincible. very serious injuries have resulted from this mindset and some of the worst injuries i have seen/heard of have occurred in padded gyms. thats said it is much safer to practice in a gym with pads rather than over concrete. just dont get the im in a gym so i cant be hurt mindset.
next the best way to learn a backflip and build confidence is to get a good spotter. find someone who at least remotely knows what they're doing. go introduce yourself to the cheerleaders if you have to and ask them to spot you

. seriously nothing can replace the usefulness of a knowledgeable spotter. even after they stop physically spotting you they can watch you when you go on your own and give you more pointers.