You have superuser in your app drawer if you are rooted.
Not sure if z4root temp root works on the desire but you cannot perm root your desire with z4root.
If you have a desire, you MUST use unrevoked. Link to rooting FAQ in my sig. Also there is a root guide there.
You did say "phone" not "desire" so with the little information you have given, this is the best I can do.