Can someone please let me know the ways to access C DLL functions through perl

There's 3 ways that come immediately to mind:

1) Use Win32::API;
2) Use Inline::C;
3) Use XS;

Note that 2) and 3) are essentially the same, but Inline::C is less complicated (IMO).
However, both 2) and 3) require that you have a C compiler.
If you have a Microsoft compiler, then you'll also need an import library (.lib) for the DLL. If you don't have the import lib, I think it could be created from the dll.
If you use a (mingw port of) the gcc compiler, you can link directly to the dll, and don't even need an import library.
There are other options as regards compilers, but I'm not familiar with them.

So ... it's really just a question of how you want to approach it. I would use a MinGW port of gcc and Inline::C.
Win32::API has simply caused me too much grief over the years, and I couldn't write an XS file by hand if my life depended on it ... but perhaps that says more about *me* than anything else.

Which path do you want to go down ?

Cheers,
Rob