Good day,
can any one please give me some explanation and an example of source codes regarding these following concepts ? I really need help, I'm so confused.

1. Access File Paths by Using the Path Class
2. Access Files by Using the File and FileInfo Classes
3. Access Directories by Using the Directory and DirectoryInfo Classes
4. Manage File Data by Using the FileStream Class
5. Manage Memory Data by Using the MemoryStream Class
6. Compress Stream Information by Using the DeflateStream Class
7. Manage Streams by Using the StreamReader and StreamWriter Classes
8. Manipulate Strings Efficiently by Using the StringBuilder Class

Thanks in advance. :)

Hi lightforce, welcome at DaniWeb!
Phew, lightforce, that are a lot of questions with information that can be found by searching here(yes here!), on MSDN or on Google. But I think you are like me in the beginning, a bit overwhelmed by the amount of information offered.
For all your file questions I should concentrate on the FileStream class first. Info about StringBuilder can be found here:
Happy computing!