First open notes to create the script you're going to be entering into terminal. You're going to need your ECID, Motherboard config, and Model ID. 
  1. ECID can be obtained by connecting phone to iTunes, on the summary tab, click on serial number until ECID shows. Copy and paste into notes. 
  2. Motherboard Config and Model ID can be obtained by downloading GeekBench 4 (You can also use BMSSM) from the App Store. 
With the info you gathered, start to build the script. Use this as the base and replace with your info. 
./tsschecker_macos -d MODEL ID --boardconfig MOTHERBOARD CONFIG -e ECID -i iOS -s 
For  8+, 
./tsschecker_macos -d iPhone10,5 --boardconfig D211AP -e ECID -i 11.0 -s 
./tsschecker_macos -d iPhone10,5 --boardconfig D211AP -e ECID -i 11.0.1 -s 
  1. Download latest version of tsschecker and unzip onto desktop from here http://api.tihmstar.net/builds/tsschecker/tsschecker-latest.zip
  2. Open terminal, type "cd", drag and drop unzipped folder onto terminal window and hit enter. 
  3. Type "chmod +x tsschecker_macos" and hit return.
  4. Go back to notes, to the script that we just made, copy and paste, hit return.
Your blobs should now be saved in the same folder as tsschecker. 
Hope this helps.