sorry, i know this is newbie question but i don't understand upgrades.

ual website reports that I have 4 "500 mile complimentary" upgrades available.

I don't understand how these are counted. Does this mean I can upgrade up to four segments?

For instance, i have two upcoming trips, one on my own, another with the family during holidays (5 ticket) . i'd truly love to upgrade with the family (although i know it is unlikely in holiday season).

So when I see this:
REQUEST UPGRADE (for all travellers), requires 2000 upgrade miles or 1 confirmed N America upgrade.

What does that mean? That I would use up the 4 upgrades (and leave one family member un-upgraded?) Or something else?

Sorry for the confusion. I have lots of miles and am apparently braindead about this whole upgrade business, so if some add'l upgrades cost me some miles, that's oK.

So, when I get to the itinerary page, and see the "request upgrade"