To install the plugin you need to go to this link here: https://wordpress.org/plugins/woocommerce/installation/
There you have a detailed description of how to install the plugin & brief description of what the plugin stands for & how it functions.
To get properly arranged with this plugin, you can follow their detailed documentation here: https://docs.woocommerce.com/documentation/plugins/woocommerce/
Set up your products
To set up your products on the plugin, please read carefully this part of their documentation: https://docs.woocommerce.com/documentation/plugins/woocommerce/getting-started/setup-products/
It is quite briefly explained, how to set up your virtual items or your physical ones. Note: For the plugin to work properly you need to check this option:
Admin Dashboard / Settings / General / Membership
You need to enable the options anyone can register.