Blurry HDMI screen mirroring issues

So, I'm trying to figure out how to hook up my phone or laptop to my TV. I stumbled upon this little gadget that plugs right into the HDMI port, but I'm totally stumped on how it actually gets power. Does it just suck juice straight from the HDMI port, or am I gonna need to plug it into a wall outlet or something?
If anyone’s got a second to clear this up for me, I'd really appreciate it!

It’s pretty straightforward. You just click the link provided and follow the instructions.
Then you'll see this:
If your TV isn't putting out enough power, connect the MirrorScreen to an external power source using a microUSB cable.

Wait, so does this thing draw power straight from the USB port on the TV? Asking because my set has two USB ports and three HDMI inputs

You get a USB cable that plugs right into the wall outlet.
I assume you actually have a phone charger lying around somewhere at home?!
If not, just head over to the nearest Walmart and look for a power adapter.