I'm assuming that your 3d face is in the current UCS.. if it's not you'll need to set it up to be. --
if your acad menus are loaded you can select the hatch command from the draw pull down menu or the draw toolbar menu. --
if not, just type "bhatch" at the command line. --
choose your pattern, i like the swatch option since it gives you an image to look at. --
set your angle (if the angle even needs to be set... in most cases it probably doesn't) --
set your scale for example in a drawing where 1/8" = 1' you would use 96 for a scale [NOTE: in previous versions of acad any patterns preceeded by the letters "AR" were already scaled to work with 1/4" = 1' (i think) so would only need a scale factor of two in the example above.. this is probably still true but I haven't tested it] --
next, select the "pick points" option and simply click once inside of your 3D face.. it should appear to be selected. press enter and your dialog box returns. click on preview to see what you are going to get.. if it looks right accept it.. if not... adjust it accordingly. --
did that work for you?