its important that the enctype="multipart/form-data"
or else it wont work;
I've had headaches with this until i relised the problem!
if File Field is called file then
you can use:
copy($file, filelocation/$file_name);
unlink ($file);
the unlink removes file from the servers temp folder. (i think 🙂 )
I do however prefer to use the FTP uploads!
look at the manual !