To blur part of a background in Adobe Photoshop, you can use the Blur tool, which is in the Filter menu. Here's a general process to follow:
1. Open the image in Photoshop.
2. Create a duplicate layer of the background by right-clicking on the Background layer and selecting Duplicate Layer.
3. Use a selection tool, such as the Lasso tool, to select the part of the background that you want to blur. Go to Filter > Blur and choose the type of blur you want.
4. A dialog box will appear, allowing you to adjust the amount of blur you want to apply.
5. Use the Opacity option in the Layers panel to adjust the strength of the blur effect.
6. Save the image by going to File > Save As and choosing the desired format.