You can manage your profile by clicking on your profile image (which may be a default logo), between the home icon and the notification icon. From the dropdown that appears, click on 'Edit your profile'.
This will bring up your profile screen where you can then edit your details and preferences. If you select the three dots across from your location these edit options will appear.
Edit profile allows you to change your details such as your location, email address, password and your 'About' section.
Editing your preferences allows you to update your interests and the causes you that are important to you.