First time mom, first time pumping

So this is my first time pumping, & I feel like I have no idea what I am doing! I did both of my breast for 10 minutes this time because I don't know what I'm doing & just encase I'm doing it wrong or I run out of milk for her I am just testing it out. But I did both for 10 minutes like I said & I got a little over 2 1/2 oz. is that good.? A quick question tho, do I pump by time or oz? With each breast? Or can anyone give me advice on pumping? Tell me what they do? Please & thank you!