Gymnastics Help? Standing up from a Backbridge?

I am a dancer, not a gymnast. But im really into Gymnastics i can do all sorts of things like Limbers,Hand walking, Differnt hand stand poses, pretty much all the simple stuff. I probably would be able to do a front handspring if i could recover from a back bridge. I cannot do it no matter how hard i try! Any tips? I can bend back in to the bridge just not stand up from it. Also, A Back walkover i can lift one leg up but not the other. I get one straight up so im pretty much doing the splits (well i am) But i cant get the seccond one off the ground! Its like its glued there !! Can you help me with theese? Tips and stuff would be nice :)