How to Make a Friend Happy

Spend time together: Relationships, in whatever form, are essential to happiness. As a result, simply spending time with your friend may make both of you happy. Make an effort to support one another and express thanks for the connection, as this will boost her satisfaction.
For example, you may show her how much you appreciate her friendship by telling her on a regular basis, such as "I simply want you to know how pleased I am you're in my life," or by sending her a letter every now and again.

Make her laugh: "Laughter is the best medicine," as the adage goes. Laughing may make you happier and healthier as a person, so make your pals laugh by telling jokes or poking (mild) fun at yourself.

Build up her self-esteem: Everyone needs to hear from time to time that they are clever, powerful, and beautiful. Don't be hesitant to tell your buddy these things since they can boost her confidence and self-esteem. Make your praises personalized for the person so she understands you actually mean what you say.
As an example, saying "I like your willingness to listen to everyone you meet. It demonstrates your concern for people." this is a more precise complement than "You're an excellent listener."
When you hear a buddy criticizing themself, attempt to reply with a compliment or some supportive words. This can assist your buddy in seeing herself more positively.


Reference
https://www.wikihow.com/Make-a-Friend-Happy