If you used Facebook or Google to create your account, your password will be the same one used to login to those services respectively and can only be changed by going to each service and changing the password there. Once changed, return to the EagleShare site and be sure to login with the updated credentials created.
If you used your personal email, and you're logged into your account, simply go to your Dashboard, click on the Account button, and then under Profile Information, locate the field named "Password" and then click on the "Edit" button. You'll be given a form field to change your password.
If you used your personal email, and you're not logged into your account, simply go to the Login Page and click on "Forgot Password". You'll receive an email with a link, click on the link and you'll be taken to a page to enter a new password.