Account details such as username and email can be changed by logging into your account on the website. You can also add a profile picture there. You can access it via this link.
Once you have logged in, your account dashboard loads, similar to the following:
You can update your account email address and password here. Once done press Save changes.
It is also possible to delete your account here, but please be careful: it is not possible to revert any changes after you confirm the deletion.
To change your username or add your First and Last name, click Edit profile and once done, Save changes.
Adding profile picture
There are two other ways to change your profile picture: click on Change profile picture option or click on your profile picture on the dashboard main page.
Drag and drop or browse for the photo you want to use and press Upload Picture.
Connect to Facebook
If you haven't done already, you can also use the dashboard to connect your account to Facebook. Just Press Connect To Facebook and voilà!
You can also update your payment method. Please check here for more information on how to do so.