Actually I created A Custom Customer Account Navigation link by using This xml
<?xml version="1.0" encoding="UTF-8"?>
<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
<body>
<referenceBlock name="customer_account_navigation">
<block class="Magento\Framework\View\Element\Html\Link\Current" name="custom-link" after="-">
<arguments>
<argument name="label" xsi:type="string">My Custom Link</argument>
<argument name="path" xsi:type="string">frontname/controller/action</argument>
</arguments>
</block>
</referenceBlock>
</body>
</page>
It Created The "My Custom Link" at the navigation links list but when I click on that link the corresponding phtml is opening in new page which is not containing customer navigation links at all on left side.How can I display that phtml beside the navigation links same like other link phtml.