When you share your project on Facebook, the project image or banner, title and text will be displayed. Below is an example on how it will appear.
1. Image: Facebook will take the project image, if not available, it will take the project banner. If not available either, they will take a random image from the page
2. Title: Facebook will take the project title
3. Text: Facebook will take a random bit from the project description
Read the article Share and Promote your Project and Tools to understand more about the social media tools you can use to promote your project.