To install the Grove library follow this link to the Github official web page:https://github.com/Seeed-Studio/Sketchbook_Starter_Kit_V2.0
Then in the right side click on"Download ZIP"button and the download will start automatically.
Locate the file, open it and navigate to the folders as showed in the images.
Copy the content of the folder to your Arduino folder (most of the cases under my documents folder).
In the next image you can see that I am coping all the folders located in the main folder.
Open your Arduino IDE, if it was open before you copied the files, then restart Arduino IDE.
Now under"File >> Sketches"you will see some examples for your Grove Starter Kit.
Now you can some examples. If you need more help you can write me on the comments sections. Happy coding!