customization – How can I embed WordPress post into my html site?

please help. Yes I can read and google. I have found a few sites also this

but it does not work.

I do not change index.html into index.php which is ok? But in this situation the php code is “white” I hope You know what I mean.
Yes I framed it but it is not what I want. I would like to have 5 last posts from WordPress being published on my html website. Please give me some hints how to make it.

Regards, Hubert