NEED HELP !!!!! 😫😫😫😫

I will be a first time mom in December! I will be breastfeeding but I also want to pump ! I honestly have no clue how it works (the freezing milk part) 
Any tips in how to store breast milk ? After being frozen for how long does it last before it goes bad ? Sorry but I really have no clue any advice will be wonderful 
Thankyou