How to add the option of sharing to Facebook and Twitter to my jotform?

members to fill out and send to their twitter and facebook accounts

It is always best to be able to set it all up in one location and have it cover as many different social networks as possible.

For that reason, I believe that this widget is the best match for what you are after: Social Share.

It will allow you to add the image, title and the link to a page to share, while in the same time offer you to share it on Facebook and on Twitter (it would of course not be able to share on both places in the exact same time, but both options would be available).

You can see here how to add the widget to your jotform: How to Add a Widget to your Form

Do let us know if you have any questions in regards to this and we would be happy to assist with them :)