Here are the steps I followed. I'm still learning but I have a workable theme I like.
Open app. Start with #1 to get your primary color scheme. By clicking on each circle, you can change the color. On the top where it says "light", this will give you white backgrounds. Click the dropdown to the get the darker backgrounds.
Now click "Advanced" on the bottom to get keyboard, AOD, Message Bubbles, QuickSettings and Notifications
Here you can create an AOD. If you choose to, turn on "Include AOD in your theme". check AOD Clock color if you want to change the color and check Image for AOD clock if you want to add an image. It will have you select the image
Now hit the back button and it takes you to #1 Core Apps. Click Next on the bottom
Now you're at #2 Third Party Apps. If you want the same color scheme, click the button "inherit". Not all apps will theme but some do such as Gmail, Google Play, etc.
If you want a different color scheme for a specific app, click it and this comes up where you can change the primary color for that app only
When done, click next for #3 Include/Exclude. Any apps you want to include in the theme, check them. Otherwise uncheck the ones you don't want to theme. Keep in mind not all will theme regardless.
Click next to #4 Build Theme. If you want to add walls or icons, check the boxes and then all the walls. When done, name your theme and click BUILD. When done, click install. Go the Samsung Theme Store and apply trial. Something is built in that will allow the theme to stay on without ending the trial. The theme will show as PROJECT [vivid] but the name of it will be your unique theme name.
Sample phone background
***I am still learning so if you come across anything new that would help other, share the tips***