PHP FTP_PUT uploading to directory

Im learning PHP by myself from a book called "PHP the Complete Reference - PHP5.2" Im currently at Chapter11 FTP, uploading,deleting,makedir etc but have run into a few questions not covered by the book:

According to my textbook this is a simple code to upload to a server:

$connect=ftp_connect("johnsite.com");
$result=ftp_login($connect,"john@johnsite","johnnyWalker");
if(!$result){
echo'Could not connect to Server';  
}
$result=ftp_put($connect,'myFile.php',FTP_ASCII);
echo'UPLOADING FILE......';
if($result){
    echo'File Uploaded!';
}

My Questions:

1. To which directory will this upload, how will I modify code if i want to upload to directory say public_html/images/myFile.jpg

2. In the example myFile.php is hardcoded, what if I want user to select a file to upload? Am I correct in assuming you can do something like this:

   <input type="file" name="myFile" value="upload a file" />
   <input type="submit" name="upload" />
   
   if(isset($_POST['upload'])){
       $fileName=$_POST['myFile']; //file is now assigned to var name
       $result=ftp_put($connect,$fileName,FTP_ASCII); //file linked to var name being uploaded
   }
   
   

3. Is this the most efficient secure way?

Thank you for reading