How do I transfer application files from a MacBook Pro to a MacBook Air?

"Transferring Files: From a MacBook Pro I want to transfer some application files to a Macbook thin air. I am not techie so what is the best way? I have come from the CD, to the thumb drive. Now what as my drives do not fit into any of the ports on any of my machines. I want to sync these files between machines."

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Getting a Thumbdrive Connection on a USB-C Only Mac:

A. Use this Adapter: USB-C Digital AV Multiport Adapter - Apple. It has a female USB-C port (so that you don't lose one), and it has the USB-A port. Along with those two ports, it has an HTMI port, for connecting it to an external screen.

B. USB-C Thumdrive:

Thumbdrives are coming about that have USB-C on them. So, look for one at your local retailer. From Amazon: USB-C Thumdrive

C. Use iCloud:

Having an Apple Account, see if you can use iCloud Drive. You'd log into it on both Macs, uploading from one, and then downloading to, the other. Go Here: https://www.icloud.com/iclouddrive

if you can get both computers onto the internet without re-cabling, you already have a highway between them, through the Switch functions of your Router. This data stops short of the internet, and just moves locally over Wi-Fi or Ethernet or both.

Then you can enable File Sharing on either or both Macs, and mount a remote folder or the entire drive of the other Mac on your local Mac, and copy files off it or place files onto it using Finder Drag and Drop.

Set up file sharing on Mac - Apple Support

Finder has always had the ability to open a second window, so that you can put the two windows side-by side and compare them to bring both up to date. Open the first window, then choose Finder > File > New window, and navigate to the other folder.