create the png file by saving it as a png file on your pc.

then, connect in mass staorage mode and transfer it to your device. if you send via bt, it will save as a jpg.

save the file in the n900 folder (or whatever you named your bluetooth...mine is called n9hundred.

thee open xterm
sudo gainroot
cd MyDocs
mv avatar.png /usr/share/rtcom-messaging-ui/html/