I've added a "gender" modification to the board. You should see by my username the new icon for a "male" poster. In order to use the modification you must enter in either "Male" of "Female", then the appropriate icon will display. To do this, simply go to your usercp, select edit your details, and enter the appropriate value for the "gender" field and then click save.
You can then come and view a post you made and see if the icon is showing up.
BTW, please use "Male" or "Female" with the capital letters. It also might take a few minutes for the modification to kick in and for you to see the icon.