No worries, this is something I can walk you through here. You would just need to save that image from Photoshop to your desktop or laptop, then upload it to your Shopify store. Shopify supports the following image formats:
If you wanted this image added to your homepage, you can to Online Store > Theme > Customise, then select where you would like to place the image. For this example, we will assume you want to add this image as a slideshow image! You can select the 'slideshow' section of the storefront editor. Here, you will see the option to add an image and upload your selected file.
If the image is coming from Photoshop, I'd recommend you make sure it is not saved with a colour profile enabled. This is an excerpt from our help pages on what a colour profile is:
To remove a colour profile using Adobe Photoshop:
Click Edit > Assign Profile.
Select Don’t Color Manage This Document.
This should ensure the image looks the same as it does in Photoshop.
Let me know what you think!
Social Care | help.shopify.com