Newbie needs help with new Sansa with drag and drop...

Just got a Sansa 2 gb and I have ITunes on my computer. I dragged and dropped some of the titles to my Sansa and it seems to have worked but when I went to Music it says it is empty…do I have to use Windows Media Player as well? I thought the drag and drop was enough…

Please - simple terms - I am not too savvy with music. Thanks!

How would I determine the file format? They were in Itunes and this was given to me by someone so I did not load the originals…

Maybe I should try to explain further. These were originally on CD’s that my son transferred from the CD’s to his iPod. I now have the iPod and in order to play anything, I had to load the music to my computer I think from the iPod (please forgive if I am not explaining this properly) through itunes. The music is now on my computer in my Music file and in there is the Itunes. I do not think he loaded any music directly from itunes and if he did, there is very little…

I just connected by Sansa to my computer and the music is showing as being in there…

My music seems to be in M4A form - I cannot re-rip the music from the original CD’s as they are not in my possession any longer - so - what is the best bet from here?
Thanks.