Again opc and .net client and wincc

Hi

I am to write an application in VB .net as a opc client of a wincc opc server on a remote computer in the same lan. sorrily i didn't have any opc exprience. as i understand i should use opcnetapi.dll or another dll as a wrapper that vendors such siemens provide it for their products for developers.does anybody here has such Dynamic Link Library or opcnetapi.dll which could help me on this case???
another problem i got is that i don't know what properties and methods is available and how should i use them in my code to read and write wincc tags. also i searched a lot but i didn't something useful,simple and brief. i also analyzed some examples in C# or excel but they were not help me in a good manner. could you please give me the keys to solve this matter???
because i'm not a opc foundation member i couldn't reach some places in their site, So please don't refer me to opc foundation.
thank you