is it easy to use Wildfire if i am skillful in Pro-e2000i

Yes. You'll need access to the menu mapper:
and a lot of patience. If you can work one, you can work the other.

If you have access to wildfire 2 , then I would highly recommend that you run through this tutorial from PTC That tutorial is meant for new users, (no previous proe experience) but after going through the phone modeling exercise you'll be comfortable in Wildfire 2. I'd been running proe since version 10 and was struggling with wildfire 2 (proe version 25) and that exercise helped me tremendously.
Also, many companies skipped wildfire 1, it was too slow and crashed several times an hour for me, so the company i was at stayed with 2001 until wildfire 2 came out. Most companies that I know followed the same pattern.

Why would you doubt your ability? Just because Pro/e has suddenly gotten popular? You went from 19 to 20 to 2000i to i-squared to 2001. You know the ropes. What's the big deal! It's just another interface change, along the trajectory of EVENTUALLY getting rid of all the Menu Manager functionality for something that's actually object oriented programming and a real GUI/WYSIWYG interface. You've taken the ride part way; don't bail now. And for godsake, DON'T PANIC!!! And yeah, I agree with the previous posts about the new resources offered on the web for 'newbies', or, as I call them, 'renoobies', for those who are coming back to Pro/e, for the first time. (Ahh, did I coin an old aphorism!?!)

The only real struggle (albeit minor) is just getting use to the changed orientation controls with the mouse, and the new picks. Menu mapper in the Wildfire resource page helps a lot to find those obscure ones. It will take you a week or so to get used to changes. Like others mentioned, take the WildFire for Existing Users tutorial. It touches on just about everything.
-mark