Creating patterns in Illustrator

I am proficient in Photoshop, however I'm attempting to create the same effect in Illustrator as I have created in Photoshop.

In Photoshop I am able to create a pattern using this process:
I create a canvas of 10px X 10px. I use the pencil tool at 1px thickness and click one pixel at a time in a diaginal pattern creating thin lines from bottom left to top right. Then I am able to select create pattern. Once completed, I am able to select anything in my layers panel and "apply pattern" to see my pattern applied to the image.

How do I do the same effect in Illustrator? Any help is greatly appreciated.