Passwordless sftp connection from UNIX to windows server

HI ,
I am trying to make a passwordless sftp connection from a unix server to windows server

I have used a existing script which is like this

cd /home150/adm/.ssh/
ssh-agent /usr/bin/ksh <<EOF
ssh-add IDBNEWKEY
ssh-add -l
sftp IDBUSER@abc.com
cd /home/IDBUSER/Share/IDB/
rm ${FILE}
quit
EOF

This script is not working and is asking for a password,in IDBNEWKEY i have pasted the private key of windows server.

Is my approach correct , what key is to be copied in IDBNEWKEY , private or public key of destination windows server or something else.

Also can someone please explain below lines

ssh-agent /usr/bin/ksh <<EOF
ssh-add IDBNEWKEY
ssh-add -l