As long as you can get one that has a throttle, you should be fine, although I do reccomend buying a joystick that can twist so you can operate the rudder.
As this program was released back in 2006, you can't buy it in the stores anymore. However, you can buy FSX on Steam, a gaming platform for PC's. Think of it similar to Nintendo's eShop on the Nintendo Wii U/3DS/Switch, or the Playstation Network on Playstation 4, or Xbox Live on Xbox One. Don't worry about DLC's for now.
Really self explanitory with the four big tabs on top the menu
I'm not ommiting something here! If you watch South Park, you'll get this joke
Now just open the throttle, put on some Danger Zone, One Vision, or whatever song you want to listen to, and enjoy the wild blue yonder.