After installing Schema Premium and configure it on your site, you will need to enable the plugin across your content.
By default; WordPress has two main post types for posts and pages.
When you install Schema plugin for the first time; it will automatically create and enable two schema.org structured data types for “Post” and “Page” post types.
You can find it under the
Schema > All Types
section.
Schema Types section is a special custom post type that is used to create and save schema.org types to be used by the Schema plugin to markup your choice of site content.
This unique feature will allow you to enable schema.org types and set content location targeting for each type across your site content.

Enabling More Schema Types
You can add a new schema.org type and enable it on your site by clicking on the
Add New
button, then follow and complete simple steps.
1- Select Schema
A new window will open where you can select the schema.org type of your choice:

After you select the desired Schema type, click on the Next button to go to next step.
2- Target Location
In this step, you will be asked to define the content location you would like this type to implemented and be enabled on.

3- Ready!
You are done, now you can edit and map schema.org properties if you need to.
Editing Schema Types
You can edit each schema.org type to modify properties per your liking.
This is how the Schema type edit screen looks like:

Once you save your modifications, the Schema plugin will start processing it though your content to output a valid schema.org markup in JSON-LD format.
You can always test structured data markup when needed.