If you want to open a blend file in Blender, follow these simple steps. First, open Blender on your computer. Once the software is open, go to 'File' in the top left corner of the screen and click on 'Open.' A window will pop up, allowing you to navigate to the location of your blend file. Select the file and click 'Open' to load it into Blender. You can also use the shortcut 'Ctrl+O' to quickly open a blend file. Once the file is open, you can begin working on your 3D modeling project. Remember to save your work regularly to avoid losing any progress. With these basic steps, you can easily open and start working with blend files in Blender for all your 3D modeling needs.