How to Add Pins
If you add it from web, Pinterest will ask you to enter the link to the website you are pinning from. After entering the link, you will reach to images of the website. Select the image by hovering over it and click the "Save" button. In the next step (as shown in the image below) add description for the image and choose the board to which you want to pin the selected picture. It also allows you to create to new board to pin the image.
If you choose to upload a pin from your device or computer. A box will appear and ask you to upload image. Click on the upload and select an image from your device which you want to pin to the board.