I suggest resteeming only a few articles at a time... most people want to see original content! I try to resteem only one article per week about. You'll definitely get the hang of it! Also, power up means to turn your "Steem" into "Steem Power." Steem Power essentially makes your account more "powerful," so your up votes on articles will be worth more, etc. You are able to cash out Steem whenever you want but Steem Power needs to be "powered down" back into Steem before changing it. Here is a link to the FAQ page that explains it better than I can haha! https://steemit.com/faq.html#What_is_powering_up_and_down