In some states you have to "ask one to be one". In other words you have to ask someone you know to be a mason to join. Some states are now allowing someone to ask you if they believe you have what it takes. You then fill out a petition. A committee will be assigned to investigate and you will be interviewed. Freemasonry is very family oriented and your wife may be asked to be there during the "interview".
For your wife there is the Eastern Star, Job's Daughters for the girls and the Demolay for the boys. It is truly a organization that the whole family can become involved if their interested.
Membership involves things such as but not limited to charity, fundraising for worthy causes such as scholarships, the Shrine Hospitals, Masonic Homes etc., other types of community involvement and a lotta good food.