Mp3's wont work?

I bought a 256 meg mini sd but they didnt have the cable. So I tried my brothers mini sd slot in his printer and it worked fine. The mp3's will go onto the card and the card sais its using like 7k memory but when I click my sounds it sais its not there...?

did you

1. put card into phone then power cycle? (turn phone off then back on)
2. put card into printer
3. open my computer and find your miniSD (should be a new drive) then select MY_MP3 folder
4. drag and drop mp3's into folder

or...

do buy your (im assuming since you said miniSD) 8100 recently? if you did your songs need to be WMA's

I love you so much. Your my hero thank you so much.