How to make your background blur in photoshop

Well I am not gonna lie to you, I am noob at Photoshop. I just recently started learning Photoshop. The reason for me to post this tutorial is for me to remember what I learn and not forget after two days and also help people around if you are looking for the same stuff. Good so if you are a pro, pleasse don't critic but your advice is definitely needed and if you are grateful by this post (; well, your welcome. So let's get to the tutorial. The tutorial is to make the background or making part of original image blur.

How to make background blur

1. First of all you need a image. Yeah you didn't know that did you? I am going to use public domain NASA image of it's Robonout 2.

Source: http://www.nasa.gov/images/content/519309main_jsc2011e017945_640x444.jpg

2. Now you can go open up your Photoshop. Double click on the backgrouund layer at the right and click ok. After that right click and duplicate layer (give any name you want)

3. From options from the top choose Filter>Blur>Gaussian Blur and choose how much blur you want (I used 5.7)

That should make everything blurry. Now let's erase the parts you don't want blurry by using erase tool. (ctrl+ or ctrl- for zoom in and out). Also choose your appropriate size from top left. Mine was a poor choice of image but I just un-blurred the wheels (because aliens told me to) to explain this. Believe me it would look super cool if you were using this to focus on a person but not a robot ;)

So there, you just learned a cool trick :)