Added a new payment method by creating a new custom module in the app/code folder and named as Payment.

Created files as follows etc->adminhtml and inside that system.xml
Code:
<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Config:etc/system_file.xsd">
<system>
<section id="payment">
<group id="termspayment" translate="label" sortOrder="2" showInDefault="1" showInWebsite="1" showInStore="1">
<label>Net Account</label>
<field id="active" translate="label comment" sortOrder="1" type="select" showInDefault="1" showInWebsite="1" showInStore="0">
<label>Enable</label>
<source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
</field>
</group>
</section>
</system>
</config>
After this we need to delete the folder in setup module in our database, And after that;
- php bin/magento setup:upgrade
- php bin/magento setup:di:compile
- php bin/magento s:s:d -f en_US –theme Swissup/argento-marketplace
- sudo chmod 777 -R /var/www/html/Szco_Supplies_Magento_Nestuite_website/
After this, it will be as shown in the screenshot below.
Screenshot:
