Automatic login on Specific Site.

Hi. I want to find a developer.
What I want to is automatic login on specific site. (https://www.cultureland.co.kr/main.do)

This site has both a PC and Mobile site. but I want only PC site.
And This site use security module. you have to solve this..

Required

1. Don't use something like selenium. only use WebRequest. (Get, Post)
2. Give me Full source code.
3. I prefer C#, but other languages are also ok.

If you wonder my project more, Please reply to me.

Thanks for reading.