creating a function block is easy.
go to POU on left lower tab
give it a name (testblock)
and a type (Function block)
and a language (ST)
type in the first programline:
now you have to declare the VARs with the declare assistant.
input1 is not a simple VAR but a input. all type is REAL
output1 is an output.
now you have made a simple adder as a FB.
examples of function blocks can be found at www.oscat.de
in german and english. download the version2 in lib and in txt and as pdf
this will give you a lot of reading.
When you have a lot of FB made you can put them in a lib. but for now just use a standard program and clean the PLC_PRG so you will keep your FB.
i sometimes export them and then i can import them in a new program, just the ones i need.
and yes we will try to give all the help you need.
and yes the docs are not very good. i would love when they would have a talk with some users to upgrade the manual.