How to make blur effects like Slinky and Secret?

Question

Design

I don't know how to code, but I want to make an effect like this for a design blog like these sites. Where do I begin ?
Example one - https://www.secret.ly/p/dkzosvkhstyjqkecpiwqrlppgx
Example two - slinky.me
My future site is powered by WordPress

Answer 1

use blur.js, example article
www.designedbyaturtle.co.uk/2013/blur-a-background...

Answer 2

Start with a graphics editor (Photoshop, Paint.NET) and play around with Blur effects: Gaussian Blur, Motion Blur, etc.