To convert Photoshop Artboard into a picture ready for use on the web or print, you need to export the artboard.
Select one or several artboards on Layers Window
Go to File -> Export -> Artboards to file
Set the Destination folder where you want to save the files.
Enable checkboxes Export selected artboards and Include Background in Export.
Select FileType from the drop-down. Configure file type options for fine-tuning the export
Press Run button. Photoshop will automatically save the files to the specified folder.
For more read about Export in Photoshop on Adobe help center