Go to https://spark.adobe.com/ and create a free account. If you already have an account, click "Log in" instead, then enter your Adobe credentials.
Click the plus sign at the top of the screen.
You are given the option of starting from a template or starting from scratch. Choose whichever is appropriate for you. Either option will walk you through what you can choose.
Your editing options will on the far right of your screen.
You can change the layout, design, and work within a theme. As you click on elements within your post you will be given more editing options.
*NOTE: Adobe Spark auto-saves as you go.
Here is a free webinar on using Adobe Spark if you want more information: How to Use Adobe Spark to Create Standout Content for Your Business
Clicking Download in the top right corner will download your design as a jpg file. Clicking Share will allow you to obtain a shareable link to your Spark creation.
For support please visit Adobe Spark Support.