Where do I fly into?

Oh, from Beijing, you should fly into Xianyang International Airport.
Upon landing, you can take airport shuttle bus line 3 to get to Main Railway Station first. Then take direct tourist bus line 5 (306) at East Square and arrive at the scenic area.

Thank you so much. Is the scenic area where we will find the terra cotta soldiers and museum? Any other attractions there? What is best way to find a guide ?

Yes, it's the place where you can see terra cotta soldiers. Other attractions in that city include Huaqing Hot Spring, Bell Tower and Drum Tower, Ancient City Wall, Big Wild Goose Pagoda and Mt. Huashan.
As there are many illegal private guides in the city, you are advised to find one from a reliable and qualified agency beforehand. If interested, you may contact this website for help. I know they have quite professional English guides. This is their contact info: traveltravelchinaguide.com
Hope helpful~

Thank you very much