sleep training

hello,

my son ethan is 14months old. i have fed ethan to sleep since birth and when he was about10 months old he would finish his feed before he was asleep, so i had to rock him to sleep and that would take about 15 minutes. it was fine till her turned 1, and it would take an hour or more for him to fall sleep. my nurse said that i have to start sleep training. my son is EXTREMELY stubben and im not sure where to start with the training.

any suggestion are would be GREAT

thank you for reading