Screen Resolutions in VirtualBox

[Bradley Sass]

Hi, I just completed a full set of installs of the three primary buntus
in VirtualBox, I even figure out how to install the add-ons and
everything. The issue I am having is I only have 3 resolutions I
selected during the text install of Ubuntu and Xubuntu. How do I go
about adding all the other ones as I am running on a wide screen laptop
and I want to use sizes like 1680x1050 and full screen.

The more detailed you are the better as this is my second week of using
ubuntu and as a fact any linux at all.

Thanks so much,
Bradley