[systemd-devel] [Install] question

[lux-integ]

Greetings,

I am trying to learn to use systemd.

I  scanned through some of the online manpages and looked at some example unit 
files.  I keep seeing

[Install]
WantedBy=multi-user.target

or

[Install]
WantedBy=sysinit.target 

or some such

I have for example a need to mount stuff (via a mount unit )  then to create 
directories and copy stuff to them
I dont know if these '/bin/mkdir'  and '/bin/cp'  tasks  can be done under 
'[Install]'

Ib brief, I dont know what [Install] is for, 
--what goes under it?
--when it is used ?
--or not used etc ?
--and I cant locate a manpage to explain it.  

I would be grateful if someone could send me the appropriate URL for 'Install' 
manpage  and or explain what it is and how it is used.


thanks in advance

luxInteg