<?php 
if (isset($_POST["gonder"])){
	if ($_FILES["resim"]["size"]<1){
		print "resim_yok.jpg";
	}
	else {
		print "resim_var.jpg";
	}
}
?>
<form action="" method="POST" enctype="multipart/form-data">
<input type="file" name="resim" >
<input type="submit" name="gonder" value="Yükle" >
</form>