How to load the block with Header,Footer,Left navigation, Right navigation in magento 2?

Create cms block and add that block id in your layout file , i.e You have created new cms block and its id is custom-block and you want to add that block in footer then in your theme's default.xml file add block code :

<!-- Footer Section -->
<referenceContainer name="footer" htmlClass="footer content">
    <container name="footer-col3" htmlTag="div" htmlClass="col-lg-12">
        <block class="Magento\Cms\Block\Block" name="footer-custom" before="-">
           <arguments>
              <argument name="block_id" xsi:type="string">custom-block</argument>
          </arguments>
       </block>
   </container>
</referenceContainer>

so this piece of code :

<block class="Magento\Cms\Block\Block" name="block-custom" before="-">
    <arguments>
       <argument name="block_id" xsi:type="string">custom-block</argument>
    </arguments>
</block>

you would need to add where ever you need to call that block :

NOTE : change block name "footer-custom" for other sections , otherwise it will load that block only once.