PHP in Templates and Template Conditionals

[Joey_Pham423]

I have tried to change the forumdisplay_thread template, which likes this:
From

	<td align="center" class="{$bgcolor}" width="2%">{$icon}</td>

To

	<td align="center" class="{$bgcolor}" width="2%"><if><img src="images/icons/smile.gif"> <else />{$icon}</if></td>

and it didn't work, so how can I you the php language to make it works?