Create a jgw file for jpg image.

Question

I converted ecw file into jpg file with IrfanView, to display the jpg as base layer in openlayers. I understood that I need to create a jgw file to display the jpg file.

I found this example:

 4.23214625853148 - A
 0.00000000000000 - D
 0.00000000000000 - B
-4.23214625853148 - E
 3404018.70881921 - C
 5819863.55539414 - F

for F - i know the left up corner coordinates(in Israel TM projection), i need other projection?

I did not understand what is the other parameter:
A is the x scale length in meters? and E its the negative?
And about D and B I have no idea.

The file is little bit big: about 300 MB, its will be a problem in openlayers?