help for use Special Mail Tags ( add page title to subject by default )

hi , first thank you so much for this fantastic plugins

i really need to put page title as subject of form ( mail) in some of my pages

i see here that it can be done :
https://www.ads-software.com/support/topic/contact-form-page-with-subject-of-post-title?replies=2

I read all instructions and help and try to do this , for example generate this code : [text subject-field “[_post_name]”]

but not success at all

it`s for my weakness in code and English , so anyone can me a sample code to do this ??

it will be great if creator of plugin put some templates of advance forms like this

i dont know how i must create a code for this ( page title subject ) for these Three blocks ( form , Mail , To: )

please help me , thanks

https://www.ads-software.com/plugins/contact-form-7/