To open a jar file with winrar, right click and click open with. Search for Winrar in that list you're given.
Also, to easily install mods, get Minecrafter. If you install mods manually (which is also permanently), it usually blocks you from survival multiplayer. But with minecrafter, all the mods are temporarily installed, AND AUTOMATICALLY (kind of like the YSmenu autocompiler). By temporary, I mean once you close Minecraft and Minecrafter the mods are no longer installed. You'll need to use minecrafter every time you want to use the worlds the mods are associated with, but other than that it's really efficient and easy. Minecrafter