Creating Ground Bitmap In Photoshop?

[b00m$iclE]

Hello, I searched for this and 41 pages of topics... and I went through the first three pages, nothing at all so now I'm posting.

My issue is that I think I'm doing something wrong with creating the image in Photoshop, Places where its not the same on the tutorial where I think I'm messing up...

Creating New file (exact specifications different in photoshop?)
Show All/Alpha Mapping (really didnt get it at all)
Saving (interlaced or normal... what settings?)

Thanks for the help.