File path: app/design/frontend/MageCheck/Tutorial/etc/theme.xml
File path: app/design/MageCheck/Tutorial/theme.xml
File path: app/design/frontend/MageCheck/Tutorial/layout/local.xml
File path: app/design/MageCheck/Tutorial/layout/default.xml
Now go to skin/frontend/ and create your package's skin folders and files as follows:
skin/frontend/MageCheck/Tutorial/css
skin/frontend/MageCheck/Tutorial/css/myStyle.css
skin/frontend/MageCheck/Tutorial/images
skin/frontend/MageCheck/Tutorial/js
skin/frontend/MageCheck/Tutorial/js/myScript.js
There you can configure the css file and javascript file to improve your custom theme design.
File path: app/design/MageCheck/Tutorial/registration.php
Now login to Magento admin panel and go to System > Configuration > General > Design and update the current theme with your new custom theme.
Go to System -> Cache Management and flush Magento cache. Open the storefront in order to see your new the applied.
To apply the new custom theme, you have to go in the admin panel, under Stores > Configuration > Design. On the Design Theme tab, select your newly created theme in the Design Theme drop-down.
To put your custom images in Tutorial Theme, you'll have to create the following structure: app/design/MageCheck/Tutorial/web/images.