Increase size of Virtual Machine?

I have set the size initially to 8 gigs and for a while, I only had 1 gig free. I used Compressor and have 3 free (I wonder if the compression slowed down the machine) - but I would like to make it bigger. I have some fear of enlarging the virtual machine and having the entire thing erased. What exactly must I do? This is using version 3 latest build.

 

Hello,

please try to use this article.

Best regards,
Stacey