Hi Betsy,
Good for you for getting in the social media swing for your amazing cards!
The best way is via your smartphone. Via your browser go to the GCU website and find the card you want. You can capture the card image you want to post by a Save Image function of our phone. Via my iphone I do this by holding my finger on the image until the options popup (Save Image, Copy). It should now be saved in your photo / camera roll. We like to use the 3D card image from the product details page.
Go to your Instagram app on your smartphone and per usual, use the plus sign at the bottom to start a post and choose an image. The default should be Library which points to your photo / camera roll. Find the photo you want and proceed per usual creating a instagram post.
Let me know if you have any questions. sometimes it's so simple it's difficult!
A few tips ...
1. in instagram you can pinch to adjust the image size and add more that one image per posting
2. portrait cards tend to translate best
3. sometimes I edit/crop my photo first to square format before uploading, instagram seems to like this
4. be sure to use these hashtags and more: #greetingcards #greetingcard #anycardimaginable #greetingcarduniverse
5. be sure to tag us @GreetingCardUniverse
Have fun, we'll be following you!