How to send a UpdateBlock packet to clients?

Let's say a player places / breaks a block. How can I send a block update packet so everyone can see what *that* player has placed / broke. (I know PocketMine does this, but I'm using a custom version that does not.)

What do you mean by custom version? Like a modified version of PocketMine?

Use PocketMine code from github

That's not simple when your using a version of pocketmine that was made half a year ago with its protocol updated for 0.12.

And why are you using it?

Steadfast
Take a look at Level->sendBlocks I guess.

Are you assuming people are stupid, or are you just trolling? This is simply too obvious and vague.