Hey I am about to make a head texture but I need to know how to get a stripe exactly down half on the 512 flat (so that I can flip it and it will be exact area on the other side). Thanks

Are you using GIMP? Also, horizontal or vertical?

If it's gimp, Go to view > Check 'Show grid'
Go to Image > Configure grid and type 256 in both of the length and with boxes under "Spacing" boxes.
That will give you a line exactly half way vertical and horizontal.
Then just use the pen tool or brush and put the dot on the line > Shift + click and hold.

The line should light up green if you have it exact.

Photoshop CS5.

And I need it vertically.

Hmm.. Sorry, can't help you there. Best thing to do is google a youtube tutorial.

When I google it I am not specific enough so nothing comes up as I want it. Thanks for you help anyway bro.

Use the Marquee tool, then the fill bucket. Tell me how it works out.

Can't find the marquee tool sorry.

Try finding a tutorial at youtube.

It is the rectangular selection tool. Select half and flip it.

Horizontal line or vertical?