Christina, I shoot quite a bit of event photography, and this is how I do it.
I get paid two different ways. I am either paid a flat fee by the event organizers or I am paid by the people attending the event- on a strictly cash basis.
Forget posting the shots on-line- you will not make much money like that.
I will give you an example of each way that I shoot events.
I have an awards banquet coming up in February. I have shot this awards banquet for the last few years. I am paid by the organizer to come in and set up an on-loction studio and shoot photos of all the attendees- either as singles or as couples with their spouse. I then provide the photos on-site, right there at the event. For this particular event, I will shoot about 100-150 couples. I have two assistants with me- one to help me handle the people and the other to man the photo printers. I run two Epson printers that print directly from compact flash cards. There is no need to hook the printer up to a computer. Of course, I carry over a dozen cards with me. When I shoot about a dozen couples, I hand the memory card to the assistant and load another card in the camera. She installs the card directly into the printer and starts making the prints. The largest size print I make is 4x6, which, when they come out, are placed directly into a nice card-stock, fold-over sleeve. The attendees are told to come back before they leave and their souvenir photo will be ready for them to take home at the end of the banquet. I also shoot PR photos of the folks receiving their awards and also snapshots of folks partying a bit after dinner. Those shots I post on a website just for fun. I leave them up on the website for approximately one month. I keep all the original files for up to one year, but it is extremely rare when I have someone who wants a re-print from an event. That is why I would advise you to forget about posting them on-line and trying to sell them that way. It can be done, and I know some event shooters that sell that way, but I am happy with the way I do it. When I walk away from that event, I could really care less if I ever hear from any of those people wanting re-prints. I want to make all my money up front and not have to worry about the hassle.
The other way is very much like the one above, except I am paid directly by the customer themselves. I live in a rural town outside of Dallas. My hometown has a big celebration every July 4th. I set up a boothe in the town square with a patriotic backdrop, lights, etc and I use the same Epson printers. Once again, the biggest print size I make is 4x6. I only charge the customer 10.00 for the shoot (which is a little under market here), but I make up for it in volume. We always tell the customer that their print will be ready in 30 minutes or less and to stop back by to pick it up. Always get the money up front when you shoot the photo.
Those are just a couple of bare-bone examples. There is more detail that goes into the shoots and if you need more info, send me a PM.
Hope this helps.