To change your Profile Picture you can do so by doing the following:

See that profile picture right at the end of your upper tab in your Home page? The one that looks like this?

Once you click on it, a pop-up window will appear giving you different options, choose "Edit Profile"

A new window will appear, this place is where you'll be able to edit every detail and aspect of your personal profile. Make sure to clock on the pencil icon right next to the profile picture area:

Here you'll meet your main "Change Profile Picture" window, simply click on "Choose Photo" to upload any file you want from your computer or mobile device, or click on "Delete Photo" to remove the current one.

Once you've selected a new profile picture a grid will appear over it for you to adjust as you wish, you'll also get a box allowing you to click on "Back" to cancel the upload or "Done" to get you one step closer to finish uploading your greatest pic!

1.5 If you're happy with how everything looks simply click on "Save" and your new Profile Picture will be set!

Admins

If you are an admin you also have the ability to change and update someone's profile picture.

Start by simply clicking on the "Search" icon at the left-upper corner on your home page.

A new window will appear, here type in the name of the user you want to modify. When you find it, click on it.

Next, you'll find yourself at the user's profile page. Click on "Edit User".

An "Edit User" window will appear, select 'Next' until you have reached the profile picture section. Once there, click on "Change Picture". Upload the file you prefer, adjust and click on "Save".

Voila! You've just updated your user's profile picture in a few simple steps, congrats!