Ask a Freemason you know about it. Don't generally expect a Freemason to ask you. The general adage is "To Be One Ask One".
Merely contacting a Mason online and desiring membership does not grant you the privilege to join.
If you don't know any Freemasons, look in your phone book and call them or search online and send an email to a Lodge in your area.
Don't be afraid to go to your local Masonic building (sometimes referred to as a "Hall", "Temple", or "Center"), knock on the door and ask someone there about it.
But please pay attention because there are several bodies self-proclamed as the "true and ancient freemasonry". That's not the truth!
Unfortunately "freemasonry" is not as a trade mark protected by law. As a paradox everybody can buy the rituals in a book-shop and establish his own Grand Lodge of Grand Orient.
The United Grand Lodge of England is the "Mother Grand Lodge" of all the regular Grand Lodges of the world. Find out on their website which Grand Lodge of your country they recognise as a regular one.
Arrangements will be made to meet you socially to find out more about you, and to give you a chance to find out more about Freemasonry.
A committee of members from the Lodge will contact you to arrange a meeting. If the meeting will be of mutual satisfaction, you will be requested to fill in the form for admission.
Your request will be balloted for membership of that Lodge.
All being well, a date would then be fixed for your admission.
You don't have to be rich to join. While initiation fees vary, annual dues usually range from about $40 to $300/year (North America).
Last but not least: each lodge (the body of members) is different than the next, so be sure to take your time in finding one that's right for you!!!