This will be very similar to the MapTools explanation. First you will want some kind of image editing tool. I use Paint.Net but there are many others available for free on the web. To get Paint.Net check out the MapTools thread as it's in the first step.
So you have your map. Position it so you can see the important bits. You'll want to trim out your user image in the lower left and the zoom bar in the upper right so position the map accordingly.
Now hit your handy Print Screen key
And drop that into your photo editing tool.
You'll want to crop out stuff you don't want to show your players. Select the Selection tool
Select your map
<img src="http://i.imgur.com/9Hw59Ill.png".
When you're readying hit CTRL + SHIFT + X and it will crop to your selection.
Now to add your coordinates so players can let you know where they are moving to. All we'll do is add text on top of the image. Make sure to specify the color and increase the size of the font accordingly.
Do that across your whole map and you're good to go.
Save it as a .jpg and just make sure the filesize is under 1 MB by using the sliders.
Now go to rPoL and as a GM click on the 'Game Map' button
Click 'Update or remove the map'
Now it shows all your different groups. Different maps are only visible to certain groups. Main Game Map is visible to everyone, Group 0 is visible to those with Group 0 access etc.
Click Browse next to the group you want to add the map to...
Once it's ready click 'Upload Maps' at the bottom
Assuming things go right, you'll see an Uploaded message next to that group map.
And there you have it! A perfectly functional map that can be used for tactical combat in your game.
This message was last edited by the player at 15:47, Sat 05 Aug 2017.