.so and .a libraries

[Morusaka]

Hi,

I have the same library (Boost Regex++ library) compiled both as a ".so" and
as a ".a" file.
I think .so means "shared object", is this right?

I am trying to compile some examples, with a sintax like:

g++ -IpathDirectory -LlibraryDirectory -llibraryName sourcefilename.cpp

it seems to compile right, but when I try to execute the program, my RedHat
system says it can't find the shared library.

How can I link to my executable the ".a" library files?

Thank you in advance, Morusaka.