How to generate Thumbnails with phpThumb and save it into a file?

i wan't to know how to generate thumbnails with phpThumb Class, with an array with file paths already. And then Save the result of each image on other path but with the same name.

Thank you all ;)

EDIT: I have my code something like this:

    echo "A iniciar gerador de miniaturas para a área de cliente: \n";
    include $wincli['files']['phpThumbClass'];
    $files = file_list($wincli['dirs']['logos']);

    $phpThumb = new phpThumb();
    foreach( $files as $file ) {
        echo "  # A converter o ficheiro '".basename($file)."' : ";
        if(is_file($file)){         
            $phpThumb->setSourceFilename($file); 
            $phpThumb->setParameter('w', 880);
            $phpThumb->setParameter('h', 241);
            $phpThumb->setParameter('q', 90);
            $phpThumb->setParameter('zc', 1);
            $outputFilename = $wincli['dirs']['logosthumbs'].$file;

            if($phpThumb->GenerateThumbnail()){
                if($phpThumb->RenderToFile($outputFilename)){
                    echo "OK \n";
                }else{
                    echo "Falhou (Ao guardar no ficheiro)\n";
                }
            }else{
                echo "Falhou (Ao gerar miniatura)\n";
            }
        }else{
            echo "Falhou (Ficheiro inexistente)\n";
        }
    }

This is the Debug:

phpThumb() v1.7.7-200612252156 in file "phpthumb.class.php" on line 216
setSourceFilename(/var/www/virtual/test.com/wincli/logos/001-0.jpg) set $this->sourceFilename to "/var/www/virtual/test.com/wincli/logos/001-0.jpg" in file "phpthumb.class.php" on line 234
  file_exists() = 0 in file "phpthumb.class.php" on line 1036
is_executable() = 0 in file "phpthumb.class.php" on line 1037
ImageMagickThumbnailToGD() aborting because cannot find convert in $this->config_imagemagick_path (), and `which convert` returned () in file "phpthumb.class.php" on line 1066
$AvailableImageOutputFormats = array(text;ico;bmp;wbmp;gif;png;jpeg) in file "phpthumb.class.php" on line 825
$this->thumbnailFormat set to $this->config_output_format "jpeg" in file "phpthumb.class.php" on line 835
$this->thumbnailQuality set to "90" in file "phpthumb.class.php" on line 852
!$this->config_allow_src_above_docroot therefore setting "/var/www/virtual/test.com/wincli/logos/001-0.jpg" (outside "/var/www/virtual/test.com/htdocs") to null in file "phpthumb.class.php" on line 1001
$this->sourceFilename set to "" in file "phpthumb.class.php" on line 754
phpThumb() v1.7.7-200612252156

"" does not exist in file "phpthumb.class.php" on line 3404
setCacheDirectory() starting with config_cache_directory = "" in file "phpthumb.class.php" on line 859
$this->config_cache_directory () is not a directory in file "phpthumb.class.php" on line 895
SetCacheFilename() failed because $this->config_cache_directory is empty in file "phpthumb.class.php" on line 2808
starting ExtractEXIFgetImageSize() in file "phpthumb.class.php" on line 2665
GetImageSize("") failed in file "phpthumb.class.php" on line 2688
$this->useRawIMoutput=false because "fltr" is set in file "phpthumb.class.php" on line 1151
ImageMagickThumbnailToGD() aborting because $this->sourceFilename is empty in file "phpthumb.class.php" on line 1196
ImageMagickThumbnailToGD() failed in file "phpthumb.class.php" on line 2695
SetOrientationDependantWidthHeight() starting with ""x"" in file "phpthumb.class.php" on line 2644
SetOrientationDependantWidthHeight() setting w="880", h="241" in file "phpthumb.class.php" on line 2660
EXIF thumbnail extraction: (size=0; type=""; 0x0) in file "phpthumb.class.php" on line 2747
starting SourceImageToGD() in file "phpthumb.class.php" on line 3005
$this->useRawIMoutput=false because "fltr" is set in file "phpthumb.class.php" on line 1151
ImageMagickThumbnailToGD() aborting because $this->sourceFilename is empty in file "phpthumb.class.php" on line 1196
Not using EXIF thumbnail data because $this->exif_thumbnail_data is empty in file "phpthumb.class.php" on line 3046
$this->gdimg_source is still empty in file "phpthumb.class.php" on line 3098
ImageMagickThumbnailToGD() failed in file "phpthumb.class.php" on line 3100
phpThumb() v1.7.7-200612252156

Unknown image type identified by "" () in SourceImageToGD()[3210] in file "phpthumb.class.php" on line 3404
SourceImageToGD() failed in file "phpthumb.class.php" on line 312

$files = array('filename.jpg', 'filename2.jpg');
foreach( $files as $file ) { // here's part 1 of your answer
   $phpThumb->setSourceFilename($file); 
   $phpThumb->setParameter('w', 100);
   $outputFilename = "thumbs/".$file;

    if ($phpThumb->GenerateThumbnail()) { 
        if ($phpThumb->RenderToFile($outputFilename)) { // here's part 2 of your answer
           // do something on success
        } else {
           //failed
        }
    } else {
        // failed
    }
}

See http://phpthumb.sourceforge.net/index.php?source=demo%2FphpThumb.demo.object.php for more info