iPod Nano, ITunes and apple Mac

Please help! I have an IPod Nano 5th generation and use ITunes on an old Windows laptop. However the laptop is getting really slow so my very thoughtful sister bought me an Apple MacBook Air 13” MacOS 14.5 in the hope I could use iTunes on it instead and it’d be quicker. However, iTunes doesn’t work on this new Mac and now I’m stuck!! I purchased a couple of tracks from the ITunes Store on my Mac and tried to sync them onto my iPod but first it asked if I wanted to sync my iPod with my library but in doing so it wiped EVERYTHING off my iPod bar the two songs I’d just bought. I then had to crank up my ancient Windows laptop again and re sync my entire library back onto my iPod. So now I’m back to square one with a beautiful Apple Mac which is near enough useless to me as I can’t add music to my iPod off it. A lot of my iPod is made up of cds I’ve ripped onto my laptop, not songs I’ve bought from ITunes Store although I do have over 100 purchased songs. What the **** is going on please guys?!