Newbie, linker error, need help

Ok now im a total newbie to programming and i have been working a program.

This program is designed to take data from the paralel port (nothing to ambitious just a 1 or a 0) and count the cuantity of 1's recieved. That does the PCint class (PC interface)

To then process a number of stadistics from them (the estadistical unit "Uest" takes care of it),

To finaly show them to the user (this is done by the USERint)


So, i have two main problems,

The first is that when i try to compile the code (with the compiler that comes with the BLOODSHEED DEV C++) it gives me the next error:
[Linker error] undefined reference to 'PCint::PCint(void)'
and so on with every class

The second is that i dont have any idea on how to recieve data from the paralel port, but this is secondary for now

so if anyone can help me out with this i would be in debt to you

>[Linker error] undefined reference to 'PCint::PCint(void)'
You forgot to define the default constructor.

>i dont have any idea on how to recieve data from the paralel port
Read the documentation to see what functions provide this support, if there are any.