Fill in layer with color?

Hi. I use PSPX & I`m having some sort of confusion problem... when I read some tutorials it says to fill in a layer with a certain color. But I can`t find where to put the HTML for that color when I click on 'New Raster Layer'. I used to think that by putting the HTML Color code into 'Highlight layers in palette' it was going to make an effect. Can someone help me with this problem? :] Oh & if you didn`t really understand what I just wrote down here, then I won`t mind explaining again since I`m sort of in a rush. Please & thanks!