I like the fact that you're asking those quetion in other to find your ways around here @tem0123 the learning curve at the hive is very long and wide and by asking question when one seems lost is one of the best thing to do.
To your question;
Staking is just a way of getting more rewards from your already earned #pob token, just scroll to your #pob balance, and press stake. Once you do this you will be abke to votes for quality contents of your choice which by so doing , it earn you some rewards from those contents you voted for.
Power up is when you stake you tokens, and the process of voting is called curation and the profit you make from curation is called curation rewards.
I will strongly advice you, to spend some times and read any quality post that comes your way, that is how i learnt most of what I know today and never stopes asking quetions when ever you are lost.
I wsih you an awesome experience on the block chain.