to the mom who have sleep trained their babies

HOW DID YOU DO IT? I've read the books, I've tried different methods but it always comes back to him screaming his lungs out. 
I feel desperate & i feel like im failing as a mother. I can't even teach him how to put himself to sleep how am I go to teach him other things, bigger things. 
He is 9 months on December 9th. Please help me, I'm so desperate. We have been doing this since he turned 6 months.