Simplified....

More steempower = more voting power.
Voting power = how valuable your upvote is

Steemitboard runs a bot which rewards newcomers with an upvote for accomplishing various milestones
It is aimed at providing something to assist in engagement and reward for minnows.

Due to the rising number of new accounts the bot can't be set to vote with full power or it will run out too quickly

By upvoting steemitboard comments/blog posts you help contribute to the amount of available steem that steemitboard can utilise to continue serving at optimum efficiency