After seeing Ocho Geek's tutorial I decided to make one...
::EDIT::
Sorry for small sizes of pics, I'll include a download with them in.
Step 1:
Open photoshop and make a new Canvas size of 512 by 512 pixels...
Step 2:
Add the texture you want to make seemless...
Step 3:
Select and copy one side of the texture:
Step 4:
Move the copied part to the other side of the texture...
(no pic)
Step 5:
Flip the copied part horizontaly
(no pic)
Step 6:
Rub out bits (do NOT rub out the edges) to make it blend with the texture..
And BANG...You have a seamless texture.
HLD
I was Jacko but I changed my name.
B I O M A S S