Linkedin - How to Receive and Give Recommendations
In the below screenshot you can see the message your contact will receive.
Now, hopefully, your contact will write the recommendation. As soon as he/she does that, you will be notified and then you are asked to review the recommendation. Just click on the "Review Recommendation" link that is sent to you.
You may choose to accept or reject it.
After you click on accept, it will appear on your profile.