输入按钮到文本区域和书写顺序

我正在制作一个简单的聊天功能。我的代码有两个问题:

1. 我希望新的帖子出现在文本文件的顶部。
2. 我想输入按钮写一些html代码到文本区，使它更容易格式化文本使用。

代码如下:

<script type="text/javascript">
forma1 = "<B>   </B>"
forma2 = "<font color="#B2E0B2">        </font>"
forma3 = "<font color="#C2E0FF">        </font>"
forma4 = "<font color="#FFC2C2">        </font>"
</script>
    <form method="post">
<div align="center">
  <input name="navn" type="text" size="30" style="color:#68748D;" value="Navn" onfocus="if (this.value == 'Navn') this.value = '';"/>
    <input type="button" onkeypress="form1('area');"/>
    <input type="button" onkeypress="form2('area');"/>
    <input type="button" onkeypress="form3('area');"/>
    <input type="button" onkeypress="form4('area');"/>
  <br>
  <textarea name="txt" cols="55" rows="5" id="area"></textarea>
  <br><br> <input type="submit" value="Send" name="submit" class="a" />
</div>
  <?php
  if ( isset( $_POST[ 'submit' ] ) ) {
    $dude  = $_POST ['navn'];
    $time = gmdate("M d Y H:i:s",time()+(2*60*60));
    $com  = $_POST['txt'];
    $fp = $file = fopen( "msgs.txt", "a");
    fwrite($file, $time);
    fwrite($file, "<br>");
    fwrite($file, '<font color="#68748D" style="font-weight:800;" size="+2">');
    fwrite($file, $dude);
    fwrite($file, '</font>');
    fwrite($file, "<br>");
    fwrite($file, $com);
    fwrite($file, "<br>________________________________________________________________________<br>" );
    fclose($fp);
   echo '<script type="text/javascript">window.location ="";</script>';
  }
  ?>
  <br>
</form>
<font><b><p>Output: </p></b></font>
<fontcolor="#000" size="2">
  <?php
  if (file_exists("msgs.txt")) {
  $file = fopen( "msgs.txt", "r" );
  echo fread( $file, filesize( "msgs.txt" ) );
  fclose( $file );
  }
  ?>
</font>

谢谢。