And then people okay with you ....?

I have great doubts regarding the issue of saves.
One thing I can not understand is verifying checksums, ask please if anyone can explain to me using the saves attached as an example.
The game is the Red Faction: Guerrillan but the question is for both games.
Any changes in Hex, which I, at the time of testing in error, shows corrupted file, or disk problem and the console off (it restarts will not turn off even).

Here are the two saves a document and the other with test changes, already googled and read about checking the checksum but I could not do in practice actually did not find where to change the scan values.
I would love the help because you want to create my own tools, but without knowing that small and main part is not possible.
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Another question, I saw that all use HxD program for editing Hex, I use WinHex for all (Romhack, Mod Saves), has a difference between programs for this purpose?

I look returns.