var userSysId = userGr.getUniqueValue();

//example code to insert a record
if (GlidePluginManager.isActive('plugin_name')) {
    var now_GR = new GlideRecord('table_name');
    now_GR.initialize();
    now_GR.user_field = userSysId;
    now_GR.field = 'value'; 
    //update additional fields here as needed
    now_GR.insert();
}

//example code to update an existing record associated with the user
if (GlidePluginManager.isActive('plugin_name')) {
    var now_GR = new GlideRecord('table_name');
    now_GR.get('user_field', userSysId);
    now_GR.field_to_update = 'value'; 
    //update additional fields here as needed
    now_GR.update();
}

//example code to update multiple existing records associated with the user 
if (GlidePluginManager.isActive('plugin_name')) {
    var now_GR = new GlideRecord('table_name');
    now_GR.addQuery('user_field', userSysId);
    now_GR.setValue('field_to_update', 'value');
    //update additional fields here as needed
    now_GR.updateMultiple();
}