Step 1: Go to your user profile page.  This is found by tapping the top left profile icon on any page of your app.

Step 2: Tap the 'Edit Profile' button in teal color.

Step 3: Lightly tap your profile picture

Step 4: You will see a popup that asks for you to choose an image from your Camera or Gallery. Selecting 'Camera' allows you to take a new picture. Selecting 'Gallery' allows you to choose from existing photos on your phone.

Step 5: Make sure to save your profile on the bottom of the Edit Profile screen.