Blender is a powerful tool for 3D modeling and rendering, and it supports a variety of file formats, including OBJ. If you want to add an OBJ file into Blender to start working with it, here's a simple guide to help you out.

Step 1: Open Blender

First, make sure you have Blender installed on your computer. If not, you can download it from the official website and install it.

Step 2: Go to File > Import > Wavefront (.obj)

Once you have Blender open, go to the 'File' menu at the top-left corner of the screen. From there, select 'Import' and then choose 'Wavefront (.obj)' from the dropdown menu.

Step 3: Locate the OBJ file

After selecting the OBJ file format, a file browser window will pop up. Use this window to navigate to the location where your OBJ file is saved on your computer. Once you find it, select the file and click 'Import OBJ' to bring it into Blender.

Step 4: Adjust import settings

Depending on the complexity of the OBJ file, you may need to adjust the import settings to ensure it looks as expected in Blender. This can include options for scaling, smoothing, and material settings. Take some time to experiment with these settings to achieve the desired result.

Step 5: Start working with the OBJ file

Once the OBJ file is imported, you can now start working with it in Blender. This may include making further edits, adding textures, or incorporating it into a larger scene.

Step 6: Save your work

After you've made the necessary changes to the OBJ file, don't forget to save your work. Go to 'File' > 'Save' or 'Save As' to save the Blender project file (.blend) so you can come back to it later.

That's it! You've successfully added an OBJ file into Blender and are ready to begin working with it. Blender provides a wide range of tools for manipulating 3D objects, so feel free to explore and experiment with your newly-imported OBJ file.