You can easily share one of your predictions by creating a new post and selecting Prediction. In order to create a new post, simply click on the floating + button that you will see appear on the bottom right of your screen on the Community and Profile tab.
Once you are in the creation screen, simply select Prediction to get started. You can add a picture, video or even an exiting YouTube video to your post. You can also select for when this prediction you are making is valid. Last but not least, you can tag your post with relevant tags to make your content more discoverable and relevant to the community.