Remember to set it higher than SC Remastered, if applicable. For example, if SC Remastered is installed in 'C:Program Files (x86)Starcraft', you should install your old version to 'C:Starcraft'. SC Remastered) installed, you'll need to install the old version to a higher directory than where the newer version is. The page presumes you're running on Windows 7 or newer.
This page will give you all the tools and knowledge you need to get Starcraft version 1.16.1 up and running for singleplayer, multiplayer, and mods.