One of the simplest way to inform readers/visitors of your blog is subscriptions by email. Feedburner is a great service that could be used for this purpose.
The first step is to create and setup your Feedburner account and the next important thing to do is to actually activate and enable feedburner email subscription. Otherwise, the following error could appear if readers try to subscribe to your site:
“The feed does not have subscriptions by email enabled” error could appear.
Follow the steps bellow:
1) Go to Feedburner.com and login
2) Click “My Feeds” in the upper-left-hand corner
3) Select your feed from the list
4) Click the “Publicize” tab
5) Click “Email Subscriptions” on the left
6) Make sure “Feedburner” is selected, and click “Activate”
7) Copy the HTML code in the box
8) Login to your WordPress blog’s administration area
9) Go to the “Appearance” section.
10) If you’re using Widgets in your sidebar, click the “Widgets” sub-tab. Add a “Text” widget to the sidebar you want, and paste the HTML code in the configuration section. Save your changes, and that’s it!
11) If you’re not using widgets, you’ll need to have basic knowledge of HTML. First click the “Editor” or “Theme Editor” subpanel, and select “Sidebar” from the list. Usually sidebar modules go between <li></li> tags; some other themes use <div>. Paste the code in your sidebar between the appropriate set of tags in the location you want, click Save, and you’re done!