This is pretty easy to do. Just see the image below and follow these simple instructions:
1. Go to blogger
2. Click on 'Settings'
3. Click on 'Posts, comments and sharing'
4. Add what you want to put in the .Comment Form Message'
I really liked . . . because . . .
I really liked the way you . . .
I enjoyed reading this because . . .
It was especially good when you . . . because . . .
I think you need to . . . because . . .
Next time you write . . .
Think about adding . . .
Have you thought about . . .
To improve your . . . try . . .
Perhaps you could . . .