If you are using an import mapping you could directly commit to the database. You can also use the mapping to crete a datastructure that you can use to do whatever you want. Once the mapping is applied, you have a regular mendix datastructure.
You would use the create activity to create and set this data. In the activity you can define your entity and set your attribute values. You can also check the setting to commit this object to the database.
I'm also going to link the learning modules. This will show you the basics and help you get started.