Preview help!

Okay, I'm trying to make a Castle Builder rip-off in my spare time and I'm having a bit of trouble. I just made an icon in Photoshop and I saved it as a .jpg (and a .psd for editing if I ever want to, of course) and I imported it into my map, but it won't recognise it as an image file! Not only that, but I don't even know what the size of a preview is so I was just hoping it would shrink it for me xD

So here are my two questions:
-What format does it have to be in?
-What size is the preview and will it automatically shrink a picture that is too big?

Try searching the site for those answers. Im pretty sure you will come upon a tutorial on it or something.

An icon must be 64x64 pixels big, and it must be in .blp format, which is warcraft's internal texture format. There are various programs that can do the .jpg->.blp conversion, I myself use Warcraft3viewer. As Azhag said, search around a bit, I know there must be some good tutorials on this topic, as I learned from one as well.

Thanks =D I'll start searching now....

You can use .tga too but they will have a greater kb size then .blp files.

Sometimes yes, but i've had less than great results using .blps for icons. I had one map where it was basically better to use .tgas. Some icons were smaller, others bigger.

Yeah for smaller images the blp compression works badly and the size is a bit more then the .tga files.
However for noobs or fast in-game testing the .tga option is a good choice :D

are you trying to put in a icon or a map preview?
icon is .blp while war3mappreview.tga has to be a .tga and in 64x64, 128x128, or 256x256 size
use photoshop to cut or stretch your picture to fit those dimensions
icons can be .tga too i think, but it takes up way too much space, dont want huge maps for people you download to know?