For this you can create a div in your main page

<div id='iframediv'>
</div>
Then in your JS code mention the following line

$('#iframediv').load('https://www.google.co.in #DIVNAME');
Here you have to replace https://www.google.co.in with the target URL. And replace DIVNAME with the target div id in the target page.

UPDATE:

This method will not work if you are accessing a page in different domain because of security issues. In that case you can do the following

create a New Server-side Page (say GetContent.aspx) in your web application (so that the domain will be same).
Then on server-side you can load the required page (from a different domain) and extract the required section. If you are not able to extract the section, load the complete page.
Then load this content to the New Server-side Page (say
GetContent.aspx)
Now you can show this GetContent.aspx using .load function. If you are using the complete page (without extracting) then use the following code for loading the required content div.

$('#iframediv').load('https://www.google.co.in #DIVNAME');