ok so i am making some decals for a ar and the compant that is going to make them for me told me this.

" *For best results, we suggest a PC uncompressed TIF format in 300x300 dpi and minimum of 12"x12" scale output. Contact one of our reps before sending the file for more suggestions.

how do i check to see if i saved the file to these specs?

The internal header for a TIFF file can be flagged for byte ordering, in either Intel or Motorola format; since nobody in the personal computing world really uses Motorola chips anymore, I'd be willing to bet that Photoshop uses the Intel format (which is what was almost certainly meant by PC in the format description). However, other than peeking into the binary innards of the output file itself, I'm not sure how to verify with certainty that PS is using the Intel byte ordering.

Size-wise, they're wanting your image size to be at least 3600 x 3600 pixels, with a DPI setting of 300.

You might ask them what bit-depth they want, too... there's no point in making a nice (not to mention huge, since it's uncompressed) image in 16 million colors if they're only going to reduce it down.

cool, so where do i set the DPI setting?

In CS4, if you make a new image from the menu (File -> New), the option is called Resolution, and it's in the middle of the pop up window. For what you're talking about here, set it to 300, and set the units to pixels/inch. If you've already started the image, you can change it in the Image Size window (Image -> Image Size from the menu).

Don't forget that your printer ignore your DPI setting in Photoshop anyhow. You set the size, the width and height of your image and the printer do as best it can.

Considering this you could just as well put a very high DPI in your image then. Like 300 or why not 600! :) (Always there are some nitwit who gets impressed. )