HELP!! Downloading files

Need help with my macbook. when I download a file and go to open it it opens with a Textfile, lots or rubbish writing. How do I set my macbook to open with the correct application and what would that application be. Will it set automatically for what ever type of file I download, any help would be great.

What sort of file is it?
You can highlight the file, go to the menu bar>file> open with>
then choose the app you want to use.

Or do a get info (+I) and, under open with select the app that you want. If you click "Change All" it will open files with that extension with the app you selected by default.

The file is a torrent software for my apple iphone. Not sure of the list of options to which im suppose to open the file with

I hope your not talking about an illegal torrent. If it's a legal one use Vuze (Azerus), Frost Wire or some other program like these. Just google "torrent client mac".