如何让音乐更换播放

<bgsound id="beij" src="" loop="-1"> <td width="87" height="164" bgcolor="#589CC8" style="border-left-style: solid; border-left-color: #FFCC00; border-top-style: solid; border-top-color: #006699; border-bottom-style: solid; border-bottom-color: #006699">                                                                                                                   
 <p align="left"><font size="2">                                                                                                                   
      <align="center"><a href=# onclick=javascript:beij.src="mid/baby.mid">背景音乐一<br></a>                                                                                                                   
      <align="center"><a href=# onclick=javascript:beij.src="mid/ita.mid">背景音乐二<br></a>                                                                                                                   
      <align="center"><a href=# onclick=javascript:beij.src="mid/snow.mid">背景音乐三<br></a>                                                                                                                   
      <align="center"><a href=# onclick=javascript:beij.src="mid/mid.mid">背景音乐四<br></a>                                                                                                                   
      <align="center"><a href=# onclick=javascript:beij.src="mid/music.mid">背景音乐五<br></a>                                                                                                                   
      <align="center"><a href=# onclick=javascript:beij.src="mid/2.mid">背景音乐六<br></a>                                                                                                                   
      <align="center"><a href=# onclick=javascript:beij.src="mid/mid2.mid">背景音乐七<br></a>                                                                                                                   
      <align="center"><a href=# onclick=javascript:beij.src="mid/baby2.mid">背景音乐八<br></a>                                                                                                                   
      <align="center"><a href=# onclick=javascript:beij.src="mid/g.wav">背景音乐九<br></a>                                                                                                                   
      <align="center"><a href=# onclick=javascript:beij.src="mid/259.mid">背景音乐十</a></font>                                                                                                                   
      </td>                                                                                                                   
    <td width="96" height="164" bgcolor="#589CC8" style="border-top-style: solid; border-top-color: #006699; border-bottom-style: solid; border-bottom-color: #006699" bordercolor="#FF0000">                                                                                                                   
      <p align="center">                                                                                                                   
      <font size="2">                                                                                                                   
      <a href=# onclick=javascript:beij.src="mid/music0.mid">背景音乐十一<br></a>                                                                                                                   
      <align="center"><a href=# onclick=javascript:beij.src="mid/music1.mid">背景音乐十二<br></a>                                                                                                                   
      <align="center"><a href=# onclick=javascript:beij.src="mid/music2.mid">背景音乐十三<br></a>                                                                                                                   
      <align="center"><a href=# onclick=javascript:beij.src="mid/music3.mid">背景音乐十四<br></a>                                                                                                                   
      <align="center"><a href=# onclick=javascript:beij.src="mid/music4.mid">背景音乐十五<br></a>                                                                                                                   
      <align="center"><a href=# onclick=javascript:beij.src="mid/music5.mid">背景音乐十六<br></a>                                                                                                                   
      <align="center"><a href=# onclick=javascript:beij.src="mid/music6.mid">背景音乐十七<br></a>                                                                                                                   
      <align="center"><a href=# onclick=javascript:beij.src="mid/music7.mid">背景音乐十八<br></a>                                                                                                                   
      <align="center"><a href=# onclick=javascript:beij.src="mid/music8.mid">背景音乐十九<br></a>                                                                                                                   
      <align="center"><a href=# onclick=javascript:beij.src="mid/pet.mid">背景音乐二十<br></a>                                                                                                                   
      </font>                                                                                                                   
    </td>  
我是这样用的