Add A Free Forum To Your Blogger/BlogSpot Blog

STEP #1:
Create and publish a new static page on your blog, exclusively for a forum. As an example, check out my forums-static-page here:

STEP #2:
Create a new forum at Nabble: Free Forums at Nabble [You will do this within 5 minutes]
Copy the HTML code...

STEP #3:
Go to Blogger Dashboard -> Design -> Edit HTML and mark the tick-box "Expand Widget Tempaltes".

STEP #4:
Find (CTRL+F) this code, in your template:

<div id='content-wrapper'>

If you are not able to find the above mentioned code, then find (CTRL+F) this one (for new templates made for Blogger Template Designer)

<div class='columns fauxcolumns'>

And immediately ABOVE/BEFORE it, paste the code you got from Nabble, with this ADDITIONAL code (Highlighted in BLUE and RED):

<b:if cond='data:blog.url == &quot;http://sunny-sehdev.blogspot.in/p/forums.html&quot;'>
PASTE_CODE_FROM_NABBLE_HERE
</b:if>

NOTE (Important): Replace the code in RED, with the link to your forum-page.

STEP #5:
Save your temaplate.

STEP #6:
This step will HIDE everything from your blog (post content, sidebar widgets etc.) and ONLY forum will be visible in your forum-page.
Find this code in your template:

</head>

And immediately ABOVE/BEFORE it, paste this code:

<b:if cond='data:blog.url == &quot;http://sunny-sehdev.blogspot.in/p/forums.html&quot;'>
<style type='text/css'>
#content-wrapper {
display:none !important;
}
.columns, .fauxcolumns {
display:none !important;
}
</style>
</b:if>

Read More about this