These lanes are designated for vehicles with a minimun number of people. In California, it usually requires only 2 people, though I have seen some that require 3. There will be signs telling you if that is the case. They are on the far left, the inside lane next to the divider. You can only enter and exit the carpool lanes where there is a break in the double lines that normally seperate it from the rest of the traffic lanes. Don'e worry they are well marked so you won't miss your exit. These breaks come up every 1 to 3 exits on average. There are some freeway exits just for the carpool lane. There is one on the southbound I5 for Disneyland Drive. It takes you directly to the parking structure for Disneyland