Can't create a folder on my newly created partition

If I have a partition: /dev/sda3 how do I take ownership so that I can create folders?

I tried:

sudo chown -R chris:chris /dev/sda3 sudo chmod -R 755 /dev/sda3

but when I right click within the folder 'Create new folder' is still greyed out?

Thanks for any assistance.

First mount your partition. Then as root, or using sudo, change ownership of the mount point to your user account with this:

chown -R you:you /mount/point/

Or, you can go to file manager and enter the mount point. Then right click and select "Open in terminal". Now execute this:

chown -R you:you /mount/point/

You should now be able create files and directories with your user account from anywhere including file manager.