After 3 years and taxes have not been paid ,how do I foreclose on the lien.

If I buy a tax lien in Alabama keep it 3 years how do I foreclose on the property

I will assume you purchased the property at tax auction and have held the tax certificate for three years ( and have been paying all the current taxes during that time)
Foreclosure in Alabama is admin and is done without court auction. If this is your first time though, use a local attorney.