Please add some rep for me if it helps thx.
Firstly download the iTunes program and install it. then make a playlist for your phone. put ur mp3 on ur memory stick under MP3 folder. for most of sony ericssons. after tt use the program tt can b downloaded from the link below.

System requirement: iTunes 4.x - 6.x and above, and Java JRE 1.4 - 1.5 and above
Unzip files to "C:\Mass-Storage-Synchronizer" and follow the instructions in the "readme.txt" file.

# Windows (zip): Mass Storage Synchronizer 1.3 (Supports Treo, Samsung, Nokia & Sony Devices)
# Clie (zip): Walkman Audio Player Skin
# Clie (zip): ROKR Audio Player Skin

this credit goes to teavuihuang
u can get further information from the link below.

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