If you are asked to create an association, what the computer is trying to tell you is that you should direct it to a program it can use to open a file.

Thus, you may have to create an association between a text file and a word processor, a photo and a graphics program, etc.

Sometimes when you click on a file --especially when it is an attachment to an e-mail -- you may get the Open With dialog box.

If that is the case, just scroll down through the list of programs until you find one that will open the file that gave you the message.

Click on the program -- say, Excel in the case of spreadsheets -- to highlight it.
If you are sure you will always be using this program with the same sort of files, put a checkmark in the box next to the line beginning "Always use ...." You create a checkmark by clicking on the line itself or the box.

The click on OK.
If, on trying to open a file you get an error message saying that program to open the file can't be found and if no Open With dialog box opens, highlight the file.

To change a file association begin by opening Windows Explorer, finding the file and highlighting it.
Then, holding down the Shift key, right-click on the file.
From the pop-up menu, click on "Open with."
Scroll down the list of programs in the "Open with" dialog box.
Click on the correct program to associate with the file.
You get a hint about which program to associate with a file by looking at the file's three-letter extension.
A file ending in ".txt" should be associated with a word-processing program; a file ending in ".xls" calls for Microsoft Excel; a file ending in ".gif", ".jpg" or ".bmp" is crying out for a graphics program.

If you run across a file with an unknown extension, browse through the list of extensions and their associated programs here:

http://www.webopedia.com/quick_ref/fileextensions.asp

If you want to be sure that the computer will always open files of the type you chose with the program you chose, click on the box next to "Always use this program to open this kind of a file."

If you think you may not want to commit the file in this fashion dont check the box; if the box is checked, uncheck by clicking on it.