Baby's sleep

My baby is now one month old and a few days. I can not get a hang of the sleep. I try to get her to sleep and she just fights it. Sometimes I try to get her down earlier and she will just sit there and take forever to fall asleep. It is exhausting to put a baby to sleep and do it for hours. Usually she gets between. 12-14 hours 14 being she had good day. The last few nights she has gone to sleep no problem.. today it has been 2 1/2 hours of trying to get her to wind down and go to sleep!