In order to use your logo as a letterhead in either a Word document or in a Google Doc, follow these instructions.
1. Click Insert, then on the Insert menu click Header
2. Choose a style that you would like to use, I suggest using the blank layout as you are inserting a photo
3. In the Header menu, click "Pictures"
4. Select your color_logo_transparent_background_small.png file
5. Resize the image according to your specifications
1. Save your color_logo_transparent_background_small.png file to your Google Drive
2. On a Google Document click Insert, then Header
3. While in the Header, click Insert again then Image
4. Click on the option to add from your Google Drive
5. Click on your image, and it will be added into the header. Resize accordingly