Here are some videos, easy to install Minecraft mods.
It’s even easier to install mods if you use a mod loader, which I do not do because I like to do it manually.
Note since 1.6 ~ it’s changed quite a bit to install mods. Currently, this is one of the easier ways to do it, I hope they quickly come up with a simple mod loader.
Here’s a 60 sec clip to install a folder, easy peasy;
If the folder does not work then it can make it through the use of other mods, FORGE may quite often cause a folder / mod is not working properly Here is a short film for manually installing mods;