What do you do when you download somthing off the internet for mac os x and text edit opens up

If TextEdit is showing a lot of strange characters it is because it thinks the downloaded file is a text file. You need to ensure you have the correct file extension (the bit after the dot in it's name) for the type of file. So, depending on what the file contains, you would need to add .mp3 for music, .mpg for an MPEG movie, .app for an application etc. etc. to the name of the file.