Hi there. Are you trying to create the second tutorial before creating the first(basic map)? You won't find *map* if you're working on the second tutorial first.
Of course if you have got that then Igloo15 is right, yes. Plus what version of PS are you using?
There is one Photoshop wich is sometimes shipped with printers which is more a home photo editor and not as powerful as Photoshop CS (or PS3 upwards) I can'tremember what it is called. Are you familiar with the User Interface?
You should find the above palette in Photoshop as standard and there you can see channels tab.
in the channels click on new layer to create a new alpha layer which should look black and it'll autoname it 'Alpha 1'.
select this layer and then paste your map in there. You then click back to the layers tab and work on that.
Happy to help if you want more info.