to upvote click the circle next to the steem dollar amount. The site is pretty new so a lot of things are still being developed, twitter looked like the back end of a donkey at first so give it time.
You build a following by creating good content and socialising , commenting on others posts, promoting your work and using the chat rooms (click the 3 lines at the top right to get there.)
use the search function to find articles about understanding steem or read the white paper (same menu as before).
oh and reputaion makes a big difference you've not got off to a great start with this post as people have flagged it. here is an article explaining reputation https://steemit.com/whales/@heimindanger/steemwhales-update-reputation-and-steem-power-withdrawal
and another on how to build a reputation https://steemit.com/steemhelp/@stellabelle/how-to-build-a-reputation-on-steemit-and-be-rewarded.