If I am rendering with blender, can I open a new project while it is rendering? If I am rendering with blender, can I open a new project while it is rendering? 

I will show you what I do when I try to open another page...

Ok, so while my project is rendering, I open up the Blender icon

This opens up a new page

I save this project

Then I open up the document(while my other project is rendering)



Then this pops up


I always thought that if I rendered something huge that would take weeks to render, couldn't I also be working with Blender on another project?
I know this a lot but it would really help me if someone figured it out...
Just open a new instance of Blender:

Windows:
Right click on the blender icon then choose Blender. This will open new blender instance.

Linux:
Just run the application another time

Mac OS:
By default, only 1 instance of an app can be run. You can work around this limitation by invoking Blender from the terminal command line. open -n /Applications/blender.app