Im new to skating?

i've only been skating for a day and i kinda have two questions.1: i can ollie its just i cant always on command.i can prolly get like 4 inches lol i know but how can i always nail it?and improve my height? and 2: i had to take out the bearings b/c one broke so i used a walsher to replace it.i had to do the same with the other truck cuz one end of the board had like a whole inch higher than the other one!would walshers work ok?its a 10$ skateboard tho.....both trucks are tighter now tho with just the walshers too.about how much would a new set of bearings cost?not anything really expensive just some that are decent.any advice(besides buying a new board) would be appreciated=]thanx