Hi LR, no worries my friend, we all had to learn too when we first started!
Do you see where your username is listed at the top portion of the screen? You will also see 'My Profile' and 'Settings' ... select Settings and that will take you to another screen where down on the left hand side you will see a section labeled 'My Settings'. Under that section there is an option to 'Edit Profile Picture'; from there you can either upload a pic from your computer or input a remote url where you have a pic that can be accessed.
Hope that helps but if not, please feel free to ask more questions!!