How to I extend the partition that Zorin lives in? (Dual Boot)

I have installed Zorin to live alongside Windows and the partition that Zorin lives in is only 40GB. By shrinking the Windows partition I managed to get 40GB more for Zorin. How do I get that 40GB of free space into the Zorin partition? Please be clear with easy steps cause I don't know a lot about this stuff, and I don't want to go through the hassle without an analytical guide.