download file and upload to “webroot/.well-known/acme-challenge/”
upload “Web.config” to webroot
verify _acme-challenge.your_domain
download the sslforfree.zip and unzip it
login godaddy plesk
select “Secure Your Sites”
select “Add SSL Certificate”
Enter “Certificate name” eg: abc.com, Country->Hong Kong, State or province->Hong Kong, Location(city)-> Hong Kong, Organization name(company)->Your company Name