SabaHao, I'd use "audacity" which needs a "lame.dll"-file to convert your projects as "mp3", if I remember it right. It's a free app, useable on e.g. a computer and the file have to be downloaded individually while there would be a portable/executable (english) version and a english/german program which could be dowloaded/installed.
I'd prefer its free features, it's also including e.g. echo / stretching sound / accelerating audio but music staying similar / just editing its sound or even cut some parts, use more lines when adding different files, etc. its file-ending for projects being "aup", I guess. Which could be a shortcut for "audacity-project"?
I could also add suggestions for video-editing apps and banners/pics, generally I'm also on discord if you prefer more detailled conversation, I'd offer pm's ere if the feature would be added for users here too.