After opening cygwin.
Step 1 - CD into the directory containing the file you want to send via CURL:
cd ../
cd /cygdrive/c/Users/[put user name here]/Documents/[more directories here]/
: "cygdrive".
2. CURL :
curl -X POST http://mywebsite.com/path/to/directory -d @some_file.extension -H "Content-Type: application/json"
"mywebsite.com...", "some_file.extension" "application/json" .