How i can install whatpulse on my lubuntu pc?
I assume it’s the same way you install it on Ubunu as Lubuntu sounds like another spin-off. 
In the download package, there is a link to a manual in the KB.
Yup! 
https://www.google.com/search?q=whatpulse+ppa^^ There’s no need to use a/the ppa, as it can be downloaded - and installed - from the download page @https://whatpulse.org/downloads/
Edit: Oh, geez!.. Keep an eye out for (things like) this, btw. xD