Hey Kajana, this depends on a lot of different factors. Specifically, what kind of computer are you using to do so? There are many different editing programs for Mac and PC - and many that are available on iPad and iPhones as well.
The "best" program depends on what device you're using, and also what kind of footage you are editing (what kind of camera). In general, the most popular standalone editing programs (we've used literally ALL of these at theory11): iMovie, Windows Movie Maker, Sony Vegas, Adobe Premiere, and Final Cut Pro.