I found \"Query using POST\" from here.
And tried to use curl command from command like. Installed curl by refering this for windows.
Here is my CURL string:
Try this. It should work.
curl -D- -u admin:password -X POST -H "Content-Type: application/json" --data
\\"{"jql":"project = CI","startAt":0,"maxResults":50,"fields":["summary","status","assignee"]}\\"
"https://myclientname.atlassian.net/rest/api/2/search"
Don't forget to use a slash (\*{}\*}after and before json