i am! i was gonna say the command button thing, so i'm glad you figured that out. i don't have a mac air and i'm still on OSX Capitan, which isn't the most recent update, so i can't help with everything but if you have specific questions i can probably help you out. :0

one tip it took me a while to figure out is that you can have multiple tabs in Finder! this is really useful when you're moving files from one place to another, but i also like to keep folders i use often open all the time.

also, if you go into System Preferences > Keyboard > Shortcuts, you can look at and change which combinations of buttons do what. the only one i ever really use is Screen Shots, but it's so helpful to know. also if you go to System Preferences > Keyboard > Text, you can have it auto-complete words or phrases if you type a shorter version. for instance, i have it set so that if i type @g, it auto-completes to @gmail.com

oh, and it's also helpful to look at/change what your trackpad does, which you can do by going to System Preferences > Trackpad. that way, you can make it so you can right-click by tapping with two fingers instead of ctrl+click and a bunch of other cool stuff.

if you're having trouble with using the trackpad, it might also be helpful for you to buy a USB mouse. i got one for pretty cheap and it's really nice to have. much less strain on your wrists and fingers.

also, if you hold down any key that has variations (vowels, y, s, z, c, l) it'll show the variations and you can press a number to type it. and! if you hold down option and press a key, it'll type a different symbol. (2 becomes ™, g becomes ©, etc.) and up at the top of the screen, next to where the time and date are displayed, there's a little symbol that looks like a box with the command key symbol and some dots in it. if you click that, then click "show emoji & symbols" you get basically every symbol and apple emoji you could ever want to use. all you have to do is open it, click into where you want to type, then double click the symbol/emoji.

that's all i can think of right now... but again, if you have any specific questions, i'm more than happy to try to answer. :>