Lose memory when writing Debian Image to uSD as well as when flashing to eMMC

Hi I am a complete newbie so request some patience.
I am working with a Rev C BeagleBone Black and have flashed the 5/14/14 image of Debian onto the board.
My issue is the reduction in memory that occurs after writing the image to my 4GB uSD as well as after flashing the image to the on-board eMMC. In both occasions, the memory is reduced to 95.7MB. Due to this reduction, I am not able to install any other software onto the board.
Would someone please explain why this is happening in the first place and walk me through the steps of how I can gain back all that memory.
I want to finally begin using this thing properly.

Thank you,

You need to find and follow the instructions for using “fdisk” to expand the size of the root file system.

“No one could make a greater mistake than he who did nothing because he could do only a little.”

“All that is necessary for the triumph of evil is that good men do nothing” Edmond Burke (1729 - 1797)