A great way to explore and learn about new places is to join a group hike.  There are many organizations that sponsor hikes and other outdoor events.  We've included a few links below known to have group hiking events, nature walks and tours in areas described on our site:

Crystal Cove Hikes & Events
Interpretive hikes and events schedule at Crystal Cove SP

Laguana Coast Wilderness Park Hikes & Events
Guided hikes schedule on the OC Parks Website

Aliso & Wood Canyons Park Hikes & Events
Guided hikes schedule on the OC Parks Website

Donna O'Neill Land Conservancy
Contact information and calendar of hikes and nature walks through the conservancy.  This place is beautiful, one of the few areas that still looks like California did 30+ years ago.  Well worth the small donation for the hike!  Many events are suitable for children ages 6 to 8 years up.
Angeles Chapter's schedule of many hiking events all over the Los Angeles/Orange County areas.
Group hikes in Orange, Los Angeles, Santa Barbara, Kern, Ventura Counties.
Several levels of informative nature walks, tours and children's programs led by Amigos de Bolsa Chica.
Tour the area proposed as a new park & preserve.  Group hikes and nature walks scheduled every month. 
Orange County native plant and wildlife educational tours for K-12 school age children.