`I'm posting the AGK code and PHP script required to make this work
`There is no need to have an html form associated with this.
`Just uploadfile.php and the AGK code.
`You must have a directory named "upload" in your server's root folder.
`Mine on my XAMPP sever is "C:\XAMPP\htdocs\upload"
`The file you are sending from the AGK code must be in your media directory

// BEGIN AGK CODE

fileID = OpenToWrite("test.txt" , 0)
WriteLine(fileID , "this is a test")
CloseFile(fileID)
cid = CreateHTTPConnection()
SetHTTPHost(cid, "1.1.1.1" , 0) // <-- MAKE SURE TO REPLACE "1.1.1.1" WITH YOUR SERVER'S ACTUAL IP

SendHTTPFile(cid , "uploadfile.php" , "" , "test.txt")
SetPrintSize(1)
repeat
    if GetHTTPResponseReady( cid ) = 1
        print (GetHTTPResponse( cid ))
    else
        print ( GetHTTPFileProgress( cid ))
    endif
    Sync()
until done = 1

CloseHTTPConnection(cid)
DeleteHTTPConnection(cid)

END

// END AGK CODE


// BEGIN PHP SCRIPT
// It is probably a good idea to do some research and add some security
// to this script as it will pretty much accept anything!
// It is important to use "myfile" as that is the index name AGK uses
// when calling SendHTTPFile()
<?PHP

if ($_FILES["myfile"]["error"] > 0){
	echo "Error: " . $_FILES["myfile"]["error"] . "\n";
}
else {
	echo "Upload: " . $_FILES["myfile"]["name"] . "\n";
	echo "Type: " . $_FILES["myfile"]["type"] . "\n";
	echo "Size: " . ($_FILES["myfile"]["size"] / 1024) . " Kb\n";
	echo "Stored in: " . $_FILES["myfile"]["tmp_name"] . " \n";
 
	if (file_exists("upload/" . $_FILES["myfile"]["name"]))
	{
		echo $_FILES["myfile"]["name"] . " already exists. \n\n";
	}
	else
	{
		move_uploaded_file($_FILES["myfile"]["tmp_name"], "upload/" . $_FILES["myfile"]["name"]);
		echo "Stored in: " . "upload/" . $_FILES["myfile"]["name"] . " \n\n";
	}
}
?> 

// END PHP SCRIPT