I've not used Partiko, but it is popular. I use Steemit or eSteem and sometimes busy.
Dapp is distributed app, i.e. any app built on a blockchain. Partiko, esteem and Steem Monsters are examples.
Mana is related to resource credits. You need this to do anything. Various sites like steemd show what you have.
You need more sp to boost your vote. If you power up your Steem and Steem dollars it will be worth more. You need around 500 sp to give 1c, but voting a lot will run down your voting power. You can still vote on posts to give them a little more. It's probably not worth voting on comments as rewards below a certain level are not paid out (dust threshold is around 2c). Leave good comments and don't worry too much about voting for now.
Thanks for your explainations and tips, esp about the voting
Posted using Partiko Android