Welcome to the board. You must be ambitious because the X-90 is a tough restoration to accomplish correctly. Use the search feature on the board(start with Aermacchi or my user name). There is plenty of restoration and parts info on the sight. Just post up if you need help.
BTW, did you get a title with the bike?
This is a 73, but it is important to look at the resto quality and the price.
Motorcycle For Sale: 1973 Harley-Davidson / Aermacchi X-90
Be cautious, there are a lot of shops and individual who claim to be "experts" but I have found most of them are hacks.