Hi,
To upload files greater than 8mb , change ur php.ini settings at
upload_max_filesize and post_max_size
if u need to send attachments from html to php, u need to say
<form name=xyz enctype="multipart/form-data" action ="abc.php">
<input type=file name=source_file>
</form>
and when at the receiving end u can do it using $_FILES
Move the file to some location in the server.
To store files in Mysql
UPDATE tbl_name
SET blob_column=LOAD_FILE(relative path of uploaded file)
WHERE id=1;
Check Mysql manual for further information