There are a number of things you need to do to complete the Loading Dock mission. Here, Chica will be the main enemy that you will need to distract.
Five Nights At Freddy’s Security Breach: Loading Dock Walkthrough
When you find yourself in the lobby area head to the food place. At the end of salads and sides, you will find a vent. Enter the vent and you will exit into a room.
In the room, you will find another vent, enter this vent and it will take you to the kitchen office. Here you will have to find the security badge.
To do that you will have to avoid Chica and enter the pizza place. When you get to this part, take the security badge but be careful as Chica will be at the door.
Here, Freddy will address and tell you that you need to order pizza through the pizza delivery system via the computer. This way you will be able to distract Chica.
When you do that you will need to follow the instructions to make the pizza. Here are the steps: first, you will add the sauce, next cheese, place the meat and finally the not meat. After this, find the oven to bake the pizza.
Then, Chica will attack you looking for the pizza. Exit the door on the right side of the pizza ordering computer.
From here you will reach the Loading Dock through the kitchen. In the Loading Dock you will find a door with a locked exits point. After the conversation with Freddy, the mission will end.