The launcher.jar will open a minecraft launcher that looks like the original (well it IS the original launcher) but the data it reads is not the normal .minecraft's.
Opening the launcher inside of the curse directory, there should already be a install of 'minecraft' ready to play where any mods will simply start like normal if you where to mod minecraft directly. If it isn't starting with mods (i.e. using normal minecraft) then you might have to go into the profile properties and change its directory from '.minecraft' to 'curse/Minecraft', but that should be done automatically.
The launcher.jar should be directly in 'cuse/Minecraft' and not in any sub-folders of the 'Minecraft' folder, if it isn't there then all I can guess is that you haven't downloaded and installed Minecraft through curse - but I doubt that's the case - in which even, if you have downloaded/installed it and it isn't there then try copying the launcher.jar file directly from .minecraft instead then create a new profile and edit the profiles directory to be pointing at 'C:\Users\(your computer name)\Documents\Curse\Minecraft'.
I honestly recommend - though - that if you are wanting to mod minecraft then you should use magic launcher instead, it's more reliable and actually works. That and it isn't to hard to use and actually gives to a real time log file (that you can clear, if it's clogging up to much ram) to look at to see if mods are breaking at all or if the game's crashed/done loading (and the log has fancy colours, who doesn't like fancy colours?).