Help needed changing colours!!

[addictingme22]

Hello, I am completely new to photoshop, never used it previous to purchasing the CS4 version.
I have been teaching myself, as I am a fast learner, and haven't been doing too badly at all.

Recently I ran in to a little problem though.
I can't seem to change the brush colour from anything more than black, grey, or white!!

I know HOW to change the colour, but if I select one, say green, it doesn't actually change it to green, but just another shade of grey..

This might be a really simple problem for a lot of people, but it is just blowing my mind!!
I would really appreciate some sort of help/info!

Thanks

 

[iDad]

Image>Mode>RGM or CMYK I am willing to bet you have it set for GrayScale ....

 

[addictingme22]

Thank you!!
I'm so new to this, that I didn't even know how to get it off of grayscale..
but I googled it and found what I needed