First lets understand the meaning of minnow?
Minnow is a small salt water fish and the word is specially referred for a small or insignificant person or organization in general terminology.

So all of us who are new to steemit and who have not yet earned a lot of steem power and vest are termed as minnows for this community or the starters in my terminology.

You would also heard of the name whale?
Whale as you all now is huge in size with respect to minnow that's why the word whale is refereed for people like @jerrybanfield, @roelandp , etc who are huge wrt to us in terms of their steem power, community reputation and vest power.

What is minnowsupport?

A project that aims to support starters, by upvoting their posts!

How do we get started?

https://discord.gg/HYj4yvw
use this link to register an account on discord and transfer 0.001 steem in minnowsupport with the memo that it gives you!

Example:

type again $register "yourusername" you will see something like this.

how to get upvote from minnowsupport?

just use this command in the post promotion related chat there.

$upvote link to your post

Example:

As for now I know this much only about @minnowsupport :)
I hope you like it. Please share it with you friends so that they can also get benefited from it.

PS: I tried upvoting my post and my friend's post using the command written above. It increased few $$'s, So yes it good investment for starters who can start to earn! :)