how can i use the computer as a storage device for my arduino so then it can read .H files produced by the GLCD bitmap converter off of the computer
I'm wondering just which part of "You can't" you don't understand? The .h extension is for files that a compiler reads. Your Arduino does not have an operating system or compiler on it, and it can not build it's own programs.
As for reading the values in a .h file at run time, from a text file on the PC, again that is not possible.
The Arduino could
send some data to an application running on the PC, informing it of the need for some data. The application on the PC could then stream data back to the Arduino, which would REPLACE data in an array previously allocated, as long as the new data streamed in fit in the existing array.
However, this requires an application on the PC that can receive data from the Arduino, and send data to the Arduino, which appears to be well beyond your skills at this time.
It also requires programming for the Arduino.