Warming Breast milk

I am a new mum and I’ve started breast feeding. I also want to start pumping and I’ve really the instructions which seems to cover everything from cleaning to storage of the breast milk including how to thaw out properly. However it doesn’t say how to warm the milk up or if you don’t.

Just need some advice on the best way to warm it up or if not too. I do have a bottle Tommee Tippie bottle warmer as t came free with the steriliser but didn’t know if to use that.

Any advice would be much appreciated.