If you want to discuss how love is shown in the novel, the best way is to look at the characters themselves, and see how they show love to one another.
The best example of this that I can think of is the very ending, when Boo Radley wants to go into Jem's room to see if he is okay after the terrific ordeal that he had to go through. Jem and Scout were almost killed by Bob Ewell, and Jem severely broke his arm. Boo was worried. Scout picks up on this, leads Boo into Jem's room, and tells him,"You can pet him, Mr. Arthur, he's asleep...go ahead...go on, sir," and then Boo lightly places his hand on Jem's head, in a show of affection and caring. Boo loved Scout and Jem; he watched a lot of their growing up years, laughed at their antics, and was so concerned about Jem that he had to touch him to make sure that he was alright.
Other characters that show love are Atticus for his children, every time he answers their questions, and teaches them morals and decency. He loves them enough to teach them right from wrong, and to care about how they think and behave. Atticus also shows a love for equality and justice as he takes on Tom's case, which he knows is likely to fail. He takes it on anyway, because he loves doing what is right, and supporting justice in the world. Cal loves Scout and Jem, as she raises, them, feeds them, and inserts teachings of her own. Jem shows love for Atticus as he is proud of his father's modesty regarding his shooting capabilities, and how he doesn't want to be found out for having lied about the Radley yard incident.
All of these characters show each other love in different ways, and each one can apply to how love is exhibited in the novel. I hope that those examples help; good luck!