Try make a new save and then close the game, reopen it and see if it did save. There's a couple of reasons why the save folder you think you're using isn't the correct one, and if you can find the correct save folder you should be able to copy and paste the saves you have into it.
If game files are modified, some games may fail to identify save files created in a previous version. BUT when i update game from 1.0 to 1.0.7 save file work with no problem.
How do I put the file into the game ? it seems i can't put the file in the www file because it is used elsewhere on my computer
You're supposed to overwrite, my dude. The whole point is to manually swap out the original for the modified, which involves getting rid of the original.
Either the mod and whichever game version you have aren't compatible or you're probably doing something off. Make sure the game is closed and none of the files in that folder are open. It won't overwrite anything that's in use.
