At the top right corner you will see:
Click on ADD.
A little box will pop up.
If you have a pic you want to add from a site you know of, click on ADD A PIN
or if you want to upload: UPLOAD A PIN
Also, if you click on the PINTEREST logo at the top, you can see what your friends are posting. Click on a pic and it will take you to the site it originated from.
ADD A GADGET
Under BASICS select HTML/JAVA SCRIPT