Problems updating rom

[Guest cargob69]

Hi.

I hope this is in the correct part of the forum. If not I am sure it will be moved.

My problem is this - I had a friend root my Desire HD last year and install a standard ROM. It did have a load of junk and splash screen from Orange prior to that. The same friend recently emailed me a link to update my phone from Froyo 2.2 to Gingerbread 2.3.3 with Sense 2.1.

However, I now want to update to 2.3.5 with sense 3.0, but I am not sure where to start and my friend is not contactable. I have downloaded ROM manager but it tells me the following:

"You must root your phone for ROM MANAGER to function. Superuser was not found at"/system/bin/su" or "/system/xbin/su. Use google search on your computer to find instructions to root your phone."

The above is word for word. The problem I have is that Superuser is on my phone, and it clearly has been rooted. Superuser does not reside in either of those (Zipped) folders however.

So, any advice? Do I need to re-root my phone or just move superuser into one of the specified folders? If so do I unzip the folder first or what? Confused.com I'm afraid :(