[FC]

What is the problem, have you read instructions for installation?

says that the file is corrupted when I try to load a mission with another map other than the standard ones. To be honest I am not sure what to do with the gui_rui.changes file.Can you tell me please where this and the TGA files should be exactly? (just in case, to be sure) Thanks anyway.

For using QMB mod you need to have sound mod or any other working mod which I suppose you have .

Than unpack content of Files folder in your Files folder and copy content of filelist.txt into your filelist.txt.

Add content from gui_ru.changes to your gui_ru.properties file which is in your files/i18n folder.

Than read instructions, not every of the new maps have full set of mission so try to chose None as a Target.

TGA pictures are just for information, they are there to show you what to set in QMB if you are not sure what to do after reading instructions.

Typical errors are extracting files in wrong folder and not adding content of filelist.txt in your filelist.txt so it's best to look if it's something of these two.