Well, if things are so bad, then before flashing your tablet you should start with learning the basics of computer literacy. So this is the first lesson for you and I hope the last.
Follow all the steps on an external PC.
1. Download the ZIP file with the modified gpt.bin file from there.
2. Download the ZIP file with the Android ROM for your tablet from there.
3. Unblock these two downloaded ZIP files. Right click on a file => choose Properties => check Unblock box => click OK.
4. Extract (or UnZIP) these two downloaded ZIP files. Right click on a file => choose Extract All => select a destination => click Extract.
So, you got the extracted files and now you know exactly where they are, because you chose their destination in the previous step. You can do all the other steps to replace the original gpt.bin file with the desired one.
Replacing the gpt.bin file you have prepared your Android ROM for flashing.
So, flash Android with flash.json first as described in the tutorial, and then do Windows as described there.