Do an Internet search for "AVI Editing Software" and make your choice. Look at the features and consider what you're trying to do. Some do basic things while others will turn out professional quality at a much higher price.
Windows Movie Maker http://windows.microsoft.com/en-US/windows-vista/Getting-started-with-Windows-Movie-Maker
"VideoFlick is a powerful video & photo editor and converter, it can also transfer video and photo from all kinds of cameras, DV, DC, clip or merge video clips, add special effects, water mark, title and share with your friends fast and easy.