SMB://NAME_OR_IP_OF_YOUR_PC/SHARE_NAME/
be sure that you look at the XML examples provided with your emulator or other homebrew you are using, most of them wilkl REQUIRE you to explicitly name a username and a password. most of the time, "guest" will work for both, but make sure your computer is giving guest access.
if you have further problems using SMB/CIFS shares with Wii Homebrew, you should get support from the same place you got the homebrew, as the community there will be able to provide you more detailed and intricate solutions and expertise.