You can use any text editor like notepad,wordpad,Ms word.

Simply open text editor and write ur text and click on close button then the dialod box appear and it ask that u want to save ur file then click yes and then another dialog box will appear on the right side of dialog box you can select the location where you want to save ur file if you want to save ur file on my computer/this PC/computer then select that location and simply click ok button.