Hi friend,
  welcome to my blog now learn setup alert message on your blog.
1. Log in to Blogger
 Now go to Blogger.com and log in to your account.
2. Go to Edit HTML
In the Dashboard page, click on template + click HTML 3. Find the code
Press Ctrl + F  you will enter the search mode. Now find the code below:

4. Paste the Code
After finding the code in your blog template, now copy all the code below and then paste that code before the code . By adding this script code into your blog template, you will begin installing the welcome messages command into your blog.

As you can see in that script code above, the sentence Welcome To My Blog indicates the welcome messages that will be appeared when visitors coming to your blog. Anyway, you can change that sentence Welcome To My Blog using your own welcome messages.

5. Save the change
By pressing the Save Template button, you can save the current change you've just made. To see the result, you can go directly to your blog. As you can see in your blog, the welcome messages will be appeared every time you visit your blog.