>OK
>
>Supose I have a small .prg
>How can I transform it in a .DLL ?
>
>Is it an easy or complicated task ?

It is not complicated.
1. You should convert that PRG to be a CLASS with OLEPUBLIC defined.
2. Add that PRG to a PROJECT and COMPILE that project as:
Single-threaded COM Server (DLL)
Multi-threaded COM Server (DLL)
Win32 Executable/COM Server (EXE)
That's all.
After you compile your project you should register that COM DLL on the user computer (if DLL use regsvr32, if EXE - NameOfTheExe/regserver)

Keep in mind that if you compile your project as DLL NO user interface is allowed.