I nevwe worked with J2ME and your question is not exact!
But:
upload:
--> via html. Generall not problem. Pls. look in any HTML docu or google.
--> via JAVA. Try http://jakarta.apache.org/commons/httpclient/ this is a great lib for this problem.
On server: generall no problem. My you need a lib for extract the file from stream.
try:
http://servlets.com/cos/
http://jakarta.apache.org/commons/fileupload/
regards Dietmar