Library Question

[Forex Trader]

Quoted from Metatrader web site:
"Libraries are user functions libraries where frequently used blocks of
user programs are stored."

I need a kick start to understanding the proper use of MQL4 libraries. How do
you access or call the functions and pass parameters to them? What do
you write and compile them as - indicators, experts, scripts? MQ4 does
not seem to offer a user function option. How does one use or convert user functions

Any help or direction is appreciated.

[MetaQuotes]

Check /experts/include/stdlib.mqh (header file, the same as *.H files in C language), /libraries/stdlib.mq4 (source) and /scripts/rotate_text.mq4 for example.