are these good instructions for wall mounted shelf

[subaru]

http://www.hgtv.com/home-improvement/build-a-simple-bar-shelf-for-extra-seating/index.html
Just want to make sure these instructions look good. I don't want this to fall off the wall. Also, how many screws should I use to secure each 2x4 to each other?

 

[z28snksknr]

should be strong enough for it's intended purpose.