Accept the defaults for the next three windows by hitting Next. Set the install destination to C:\Diablo II if it was not set already. Download the D2SE installer D2SE_V2.2.0.exe from and run it. Run the LODPatch_113c.exe to update Diablo II to 1.13c. (This makes the folder easier to find and you don't have to deal with User Account Permissions)
Extract the folders Original and Expansion and install them directly on to your C: drive accordingly. Using the download links in this thread You will download the DiabloII_113c_Installer.zip and LODPatch_113c.exe.
