A Very important Skateboarding question?

i recently bought a world industries 50/50 skateboard. i have had it for quite some time now nd i dont seem to learn anything on it. it came as a complete but i added thunder trucks and these orange pro wheels..plus when i trie to ollie i get maybe two inches off the ground but i cant seem to slide up my foot all the way...........please i need help i live in newark nj