You can get shopping cart details using block, Check link, Get details of Shopping cart items.
For create a simple module, Refer link, Create Simple module in Magento 2
You need to start with basic module creation, Registration.php file is for register our module. Create registration.php file,
<?php
\Magento\Framework\Component\ComponentRegistrar::register(
\Magento\Framework\Component\ComponentRegistrar::MODULE,
'Rbj_Customer',
__DIR__
);
Create module.xml file,app/code/Rbj/Customer/etc/module.xml,
<?xml version="1.0" ?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:Magento:framework:Module/etc/module.xsd">
<module name="Rbj_Customer" setup_version="1.0.0"/>
</config>
Create Block file, app/code/Rbj/Customer/Block/ShoppingCart.php and template file at app/code/Rbj/Training/view/frontend/templates/index.phtml
Refer blogs for Block and template file data, Get details of Shopping cart items.