It's probably too easy to make animation.
In the case of using Nesticle, note how you can save screenshots. Well, just take a screenshot for every frame (or image) you want in the animated picture. Then by using a picture editor, you can get the frames you want and make them into an animation.
Making an animation can be tough if you don't have the right tools. The most famous animation type is gif. You just put all the frames you want into it, then it will automatically run the animation for an infinite amount of times when you put it on your website and access it.
Finding a program that allows you to make gifs is the only problem. I can assure you that there are some free programs that you can use to make your own gifs. There's even a gif editor over at Tripod's Animated Gif Gallery that you can use to cheat and make your own gif.
But if you're serious about animation, you better find a gif program. You can also make a video file instead. There's a program called IconForge that can make videos, as well as icons, cursors, and animated icons and cursors. However, while it can make gifs, that option is reserved for the registered version.
Videos allow even more colors than gifs, but they take up a heck of a lot more space doing so. So it's not recommended if the only animations you plan to use come from NES or SNES games. Videos can also run when you put them up on a webpage, and you have control over how many times it plays.
May Yoshi live long and prosper...
Oh, and may PenguinWizard have the same treatment.