If you are talking about an email capture to build a list, I think you need to use mailchimp or someone else. The best way to capture emails & build a mailing list?

If you mean an RSS button for visitors to subscribe to receive notices of new posts on your website, then there is a WordPress widget for that. It is called RSS. Just drag it to your sidebar and set it up. I haven't done it but this WP help link might help.

https://wordpress.org/support/topic/how-to-add-a-rss-feed-to-my-blog

Tom

You mean on youtube?
I have info on my website about that
http://workathomefuture.com/youtube-subscribe-button

I use mailchimp.

To receive followers, you need to post your social network links on your site, perhaps on your About Me page or using a social media plugin if your theme doesn’t have the option for social site links.

As for the comments, all you need to do is make sure you tick “Allow people to post comments on new articles”. To do that, go to Settings – Discussions - Default article settings - Allow people to post comments on new articles.

Hope this helps =)