All states have different laws. In CA, you are required to have a license.
There are two ways to get a license:
1) Take a class.
2) Pass the PTCB and get certified. (Then, you file for your license with the state board. License and certification are two different things.)
A lot of places (Kaiser, Rite Aid, Longs) will hire you as a cashier and then send you to classes to get your tech license (I think you get paid to do the classes too.)
I took a class; I liked doing this because it placed me in an internship which gave me experience before I went to go find a job (and the internship turned into a job, which was super easy). A lot of people prefer just taking the PTCB. It's up to you. If you just want to experience pharmacy, working as a cashier will probably be enough and you can see if you want to continue on to be a technician.