If you make changes to your development database and refresh the schema model page, these changes should show up.  You can click on an object at the top to see how it has changed at the bottom.  

You can also multi select objects using Shift + Click.

If you select any changes you want to capture, and then click Save to project, each change will be saved as its own CREATE DDL script in the schema-model folder under your project.

If you go to your project folder or click on the link to the Schema model, then you can see how this is stored on disk:

Run the diff command to get the list of differences and generate an artifact

$ flyway diff -source=development -target=schemaModel

Flyway Enterprise Edition 11.2.0 by Redgate
Licensed to red-gate.com (license ID 1174ed6b-b10e-41bd-9a1b-285ddc3239c7)

See release notes here: https://rd.gt/416ObMi
diff artifact generated: C:\Users\Flyway\AppData\Local\Temp\flyway.artifact.diff
+-----------------------------+--------+-----------------------+----------------+---------------------------------------+
| Id                          | Change | Object Type           | Schema         | Name                                  |
+-----------------------------+--------+-----------------------+----------------+---------------------------------------+
| YoZgVMdZR3p7FZEygVaRX9MoF2w | Add    | DDL trigger           |                | ddlDatabaseTriggerLog                 |
| ZKZljmz2_Vvl5wLmV.mczvanHzM | Add    | Extended property     |                | MS_Description                        |
| VYj3ZC0OtkZR4CbJ_JHm9BMkg_c | Add    | Full text catalog     |                | AW2016FullTextCatalog                 |
| qlJstpTbyOQ7nRXTfUvY4lnUDIA | Add    | Function              | dbo            | ufnGetAccountingEndDate               |
...
| YreyZ8E1z3onEQFgWSGvDqaDUeY | Add    | XML schema collection | Production     | ProductDescriptionSchemaCollection    |
| UJr0Z.pCcr8O5ntP1w6H9teL8kQ | Add    | XML schema collection | Sales          | StoreSurveySchemaCollection           |
+-----------------------------+--------+-----------------------+----------------+---------------------------------------+ 

Running the model command to update the schema model folder

$ flyway model

Flyway Enterprise Edition 11.2.0 by Redgate
Licensed to red-gate.com (license ID 1174ed6b-b10e-41bd-9a1b-285ddc3239c7)

See release notes here: https://rd.gt/416ObMi
Saved to schema model
 File updated: C:\Users\Flyway\FlywayProjects\SqlServerProject\schema-model\Database Triggers\ddlDatabaseTriggerLog.sql
 File updated: C:\Users\Flyway\FlywayProjects\SqlServerProject\schema-model\Extended Properties\MS_Description.sql
 File updated: C:\Users\Flyway\FlywayProjects\SqlServerProject\schema-model\Functions\dbo.ufnGetAccountingEndDate.sql
 ...
 File updated: C:\Users\Flyway\FlywayProjects\SqlServerProject\schema-model\Views\Sales.vStoreWithContacts.sql
 File updated: C:\Users\Flyway\FlywayProjects\SqlServerProject\schema-model\Views\Sales.vStoreWithDemographics.sql

Note that the diff command is generating an artifact to a temporary directory that the model command is then using to perform the update operation. This will not be cleaned up although it will be overwritten the next time the diff command is invoked. You may want to configure an explicit artifact location instead.

This tutorial has implicitly selected all the differences in the update. A subset of changes could instead be selected using the ids that appear in the diff output.