I’m filing separate from my husband and I’m trying to figure out how to put him down as a member of the military but I don’t exactly see how to do so?

I’m in the very beginning and it doesn’t seem to give me an option to put if he is or isn’t, then when I go to review the information it says that he’s not a member of the military. I’m not quite sure what to do or how to go about putting that in.