Photoshop question

[Killer_Rubber_Ducky]

So, im trying to follow this tutorial http://www.armaholic.com/forums.php?m=posts&q=13680

I can not make any sense out of the Photoshop section.
Mainly Step 2 is where I get lost. I can resize the image but after that I can't decipher what he is saying. Can someone break it down for me? just step 2 really.

[erocker]

The way I'm reading it, it is self explanatory. Go here: http://psd.tutsplus.com/ and use the search feature for specific questions as you go along.

[Killer_Rubber_Ducky]

this is the confusing part for me. I can not understand what he is saying.

Now we need a mask for the textures to match our sat_lco photo so we make a mask out of the sat _lco.png image

Now put the sat_lco image in PS make a new layer on the sat_lco on my map i will pick yellow for my desert area take down the RGB numbers top right of PS screen these are vital so get it right now colour the areas that are desert on the top layer .

when done move on to the grass areas pick a green take down RGB numbers mask over the green area we will do just 2 as a guide so now you should have this: