I keep the ammo in the original bag and sometimes put that bag into a thicker lip lock.
I then get a handful of bbs and put them into the speed loader and load the mag. Pretty simple. Going on 14 years and this works best. Be happy you don't have to use the loading tubes of the old days.
I carry 6-12 mid-capacity and low capacity magazines. This can last me half the day normally. Sometimes I'll carry a hicapacity magazine or two as well at low key games.
Running Android's LM4 with 8 magazines tended to last me 2-3 hours at skirmish games and all day/weekend at the MSW game I attended with it.
Also, get used to sarcastic replies to your rookie questions. Don't be a squish mitten in response.