you do or don't know so I'll start off simple. Please don't be insulted.
Disney has generally two types of dining options, tables service (TS) and counter service (CS). People can make Advanced Dining Reservations (ADRs) at TS locations. This essentially gets you the next available table at a specific time. CS locations are similar to fast food palces. It's first come first serve. Food is ordered at a counter and carried to a table.
Summer is a high season and TS ADRs, especially for eight, are going to be difficult. Don't count htem out though if you want to try. If you want to try, you'll need to be very flexible. You can continue to call even after you are on site or even stop at a Guest Services location. The number is 407-939-3463 (407-WDW-DINE).
There are various options in the parks and rersorts. The parks and resorts each have CS and TS locations with the exception of the value resorts (All Stars and Pop Century) and POFQ. Quality and taste vary. This site has sample menues for each location. These are grouped by locations which makes it easier to narrow down options if you know where you will be toruing:
http://www.wdwinfo.com/wdwinfo/dining/disneydining.cfm
I mentioned above that quality varies. This is a link that collects and averages reviews from various people. It's useful to narrow down options in a short period of time. The restaurants are grouped similarly:
http://land.allears.net/reviewpost/
Some TS locations are character meals in which characters mingle among the tables for pictures and autographs. The menu list above generally identifies who the characters are. Some of the favorites are Crystal Palace (CP), Chef Mickey's (CM), Cape May, Ohana, Garden Grill and Tusker House. These tend to be a little more expensive because you are paying for the convenience of meeting characters. They are also popular for the same reason so they may be hard to get, but don't give up. If you miss out characters can be found throughout the parks. Toontown Fair in the Magic Kingdom and The Character Meet (name?) in Epcot usually have a few. Cast members (CMs or Disney "employees") can help you find others.
Some of the easier TS locations may be Biergarten, Trails End, Whispering Canyon and Boatwrights. Some of the better CS locations are:
Magic Kingddom - Columbia Harbor House, Peco Bills and Cosmic Rays
Epcot - lot's of them; Sunshine Seasons, Tangierien Cafe, Yorkshire Fish House, Cantina de San Angel, Sommerfest
Disney Hollywood Studios - lesser choices; Pizza Planet, Backlot Express
Animal Kingdom - Flame Tree Barbq and Pizzafari.
Maps of all of the parks, as well as times guisdes for parades and shows, are available as you enter the park. If you want to look before getting there this next link has scans of the maps available in the parks.
http://www.wdwinfo.com/maps/index.htm
One note, with this being high season the CS locations will get busy at normal lunch times. Sometimes seating can be diffidcult to get. If you plan around slightly off hours seating is easier.