Opening OBJ files in SolidWorks allows you to work with 3D models from various sources and use them in your designs. Here's a step-by-step guide on how to do it:

1. Launch SolidWorks: Start by opening SolidWorks on your computer.

2. Click 'File' Menu: Once SolidWorks is open, go to the 'File' menu at the top left corner of the window.

3. Select 'Open' Option: From the dropdown menu, select the 'Open' option to begin the process of importing the OBJ file.

4. Choose File Type: In the file dialog box, select the 'OBJ Files (*.obj)' option from the dropdown menu next to 'Files of type'. This will filter the files displayed to show only OBJ files.

5. Locate OBJ File: Navigate to where the OBJ file is saved on your computer and select it.

6. Click 'Open': Once you have selected the OBJ file, click the 'Open' button to import it into SolidWorks.

7. Adjust Import Options: Depending on the OBJ file, you may be presented with import options to adjust how the file is imported into SolidWorks. You can modify settings like units, scale, and orientation as needed.

8. Complete Import: After adjusting the import options, click 'OK', 'Finish', or 'Next' to complete the import process.

9. Work with OBJ Model: The OBJ file should now be imported into SolidWorks, allowing you to work with it as a 3D model. You can make modifications, assemblies, and designs with the imported OBJ file as part of your SolidWorks project.

10. Save your Work: Once you have made the necessary changes or additions to the OBJ model, remember to save your work to ensure that the modifications are preserved.

With these steps, you can easily open and work with OBJ files in SolidWorks to incorporate 3D models into your design projects. Whether you're collaborating with others or integrating models from different software, SolidWorks provides a seamless process for importing and using OBJ files in your 3D modeling workflow.