I am sorry you are having issues in locating the IPSW file. However, downloading a file (and where it is put/named) is a function of each individual's computer and browser. No tutorial can possibly be written to cover every possible combination/set-up of personal computers and individual knowledge.
What we can do is help you keep chipping away at this. But, since it's now a computer issue, not an iPad issue, know that doing this via print is going to become a little frustrating for you. So, hang in there and we'll get this sorted. Or, if you can, ask a live person in your area to help you with the download? May be easier than us trying to tell you over the Internet...?
On your specific download question - have you tried a search of your computer for the .ipsw extension? You can search the whole comput and, tho it will take a while, it'll find it.
If you open your C: drive folder (click Start, select Computer), do you get a Windows Explorer window? On my Windows 7 PC, when the window opens, I get a list on the left side. One of the items in that list is my "Downloads" folder. If you get the folder with the list - is that IPSW file there?
Or, you can download, once again, the IPSW file and this time, put it on your Desktop of your laptop. This way, you can guarantee that you know where it has been put.
Try these suggestions to find/get the IPSW file. Again, I'm trying generic questions because everyone's computer set-up is different. Hopefully, this'll get you close to that file.
Keep us posted?
Marilyn