Use open ftps://username:password@ftps.host.com/

See
https://winscp.net/eng/docs/scriptcommand_open
https://winscp.net/eng/docs/session_url

No need to specify a port as 990 is a default port for ftps://.

I was able to connect from GUI of WinSCP but can't connect from the comand line.

In the latest beta/RC version you can use Generate Session URL function:
https://winscp.net/eng/docs/ui_generateurl

Hello,

This is my first post.
Do you have any sample code to connect to FTPS server.
I have
1.username
2.password
3.port: 990
4.hostname: ftps.host.com
5.File Protocal: FTP
6.Encryption: TSL/SSL Implicit

Need to automate the process to open connection from my server and send/get files.
I was able to connect from GUI of WinSCP but can't connect from the comand line.

Thank You