Disney only sells Annual Passes, which are good for 365 days from the date of activation. (aka first day of use).
Season Passes are Passes that expire at the end of the year. Six Flags sells this type of pass. Universal and SeaWorld offer both Season Passes and Annual passes.
Second, have you already paid for an Annual Pass?
If you haven't, you have to go to the Main Entrance Ticket Booths to purchase your AP before entering the parks.
If you have a Costco AP Voucher, that also must be redeemed at the Main Entrance Ticket Booths, so you can get your $50 Gift Card.
If you have the "Gift Card" that is sold at the Disney Stores and many Supermarkets, you can take that directly to the Disneyland Turnstiles and they will scan the voucher and let you into the park.
If you have the "e-Ticket" Print at Home Voucher from Disneyland.com, you also go straight to the turnstiles, but this time they will scan your print out and then keep it, and issue a "cardboard" voucher right at the gate.
Now, how do you get your "Plastic" Annual Pass with your photo?
If you went to the Main Entrance Ticket Booths, and have a photo already on file (That is having an Annual Pass in the past 4 years or so), then they will just print your AP at the Ticket Booth, and there is no need to go anywhere else.
But if you skipped the Ticket Booths or did not have a photo on file, after entering the park, you will need to go to the Plaza Pavilion.
To get to the Plaza Pavilion, walk down Main Street to-wards the Central Plaza, and stay to the left side of the street, when you get to the wait board near the entrance to Adventureland, stop and turn around. You should see the Plaza Pavilion. Get in line with your voucher. (And if you have vouchers for the entire family, everyone needs to get into line so they can get their photos taken).
They will take your voucher, ask some questions such as address and date of birth, take your photo and issue the Plastic AP.
Also, if you have a Park Ticket, such as a ParkHopper you used to enter the park that day, and want to upgrade to an Annual Pass, you go to the Plaza Pavilion. They will take the ParkHopper, scan it and find the amount paid for the ParkHopper and then give you credit for the amount to-wards any Annual Pass that is of equal or greater value. They can collect the money, or if you are a Southern California resident, even set up the monthly payment plan at the Plaza Pavilion.
I have an annual pass myself but since I am still half asleep apparently I typed "season pass". Sorry about that. I was just checking for a relative who is coming for her birthday and wants to upgrade her ticket to an annual pass.