Process of obtaining visa/citizenship

Hello, all! My name is Jean. I'm currently in Pennsylvania, USA and am hoping to move to Sint Niklaas, Belgium at some point in the future. I know that this likely won't be an easy process, but there's a woman there who has stolen my heart. Since it's not feasible for her to move here, I am hoping that I might be able to gain some insight into what is required to potentially move to Belgium.
Please feel free to offer any information you can as I am completely lost on where to begin. I am a former Military Brat (father served in the US Air Force), but I have never technically been out of the country. So I know that the first step is to obtain a passport.
I know that this will not be a quick process, which is why I am starting to research now. The more I know going into things, the better I will feel about trying to go and be with the woman I hope to make my wife. I have no one I can ask over here.
Thanks in advance for any information you may be able to assist me with. I simply want to make sure that I do everything "by the book" so that it doesn't come back to haunt me later on.
Jean