iPhone 3GS will not transfer mp3 from my computer to my iPhone 3GS (ios4)

[Mupkins]

Hi - I have been trying for months to transfer mp3 or music items from my computer (running windows 7) to my iPhone 3GS. I have read so many articles that all basically say to set up a 'file' or 'library' in iTunes and then sync selected/ticked files etc. I have tried to do this many many many times and am now getting really annoyed that my iPhone/iTunes will not transfer these items. I am currently running IOS4 on my iPhone because I was told that updating to IOS6 has lots of problems including wiping everything from your iPhone. I also get an error message from Apple on my iPhone 3GS when it asks me for my user/password details DESPITE THEM BEING CORRECT! This is so frustrating...

 

[durruti]

Add audio files to your Itunes "Library".

After that, create playlists.

After that, click and drag the playlists to to your iphone icon in Itunes.

 

[Mupkins]

Thanks Durruti. I have tried to 'add' audio to my iTunes Library but it won't let me. I keep getting a red circle with a cross through the centre. I have already copies the mp3 files from my computer into a 'playlist'. I have even copies the mp3 files to my 'music' folder of the 'Library' but they still won't 'sync'. Am I being a numskull?