Running a Doom one WAD on GZDoom?

[Frisky]

I'm trying to load my Doom1.WAD on GZDoom, but it tells me I can't "-file" it because it's Shareware and then it says "Register!".
Can somebody help? :(
I want to play Brutal Doom on it...

[Edward850]

Buy Doom. You can obtain money by mowing lawns.

[Mithran Denizen]

Doom1.wad is the free 'shareware' version of the game. You need the full version to run mods like Brutal Doom.

Buy Ultimate Doom if you haven't already.

[snapshot]

use -iwad (followed by directory and filename) , Not -file .

[Da Werecat]

I'm sure DMGUYDZ64 just wants to help, but nearly all of his suggestions are either aimless guessing or completely missing the point.

And I'm only saying "nearly" in case I missed something.