Installing Blinka and CircuitPython libraries is very easy using Thonny. It has a built-in file transfer feature that makes copying the files very easy.
A files pane should appear on the left side of the main window. You can resize the elements to make it easier to see. Your local files should be at the top while the files on your Raspberry Pi Pico are on the bottom.
To upload, right-click on a folder or file, choose Upload to and it will upload to the current folder you are in on the Pico.
Install Blinka and PlatformDetect
Blinka and PlatformDetect are both required to run Blinka on MicroPython. Neither of them are included in the bundle, so you will need to download them from GitHub. You can download the latest releases from GitHub by following these links:
Once you have downloaded the release files, go ahead and unzip them using your favorite zip utility software and place the files in a safe location such as your desktop.
To install the PlatformDetect, use Thonny's Files pane to navigate to the location where you unzipped the files and upload the adafruit_platformdetect folder to the Pico.
To install the Blinka, navigate to the location where you unzipped the Blinka files and upload everything inside of the src folder to the Pico.
The easiest way to do that is to go inside of the src folder, highlight everything, right-click, and choose Upload to.
Install CircuitPython Libraries
First start by downloading the latest CircuitPython library bundle from circuitpython.org.
Download the adafruit-circuitpython-bundle-py-*.zip bundle zip file, and unzip a folder of the same name. Inside you'll find a lib folder. The entire collection of libraries is too large to fit on the Raspberry Pi Pico. Instead, add each library as you need it, this will reduce the space usage but you'll need to put in a little more effort.
Like you did with Blinka and PlatformDetect, use Thonny's File Transfer system to navigate to the bundle folder. Select any library files or folders you want to transfer, and select Upload to.