Theory:

     But Shree doesn’t do her homework. Instead, she starts the computer, goes online and waits for her new friend to ping her. Soon she gets a message from Chaitra.
 
     “Hello, friend. How are you today?”
 
     “I’m fine, I didn’t eat my tiffin,” types Shree. “Why?” types Chaitra.
 
     “Because I wanted to talk to you. So I finished tea quickly,” types Shree.
Explanation:
 
Shree told her aunt that she was going to do her schoolwork, but Shree didn't do that. Instead, after her aunt had gone to sleep, she opened her computer and prepared to have a chat with Chaitra by being online. She was expecting a message from Chaitra.

As expected, she received a message from Chaitra. Chaitra started to type. She addressed her as a friend and inquired, "How are you today?". Shree was happy about her new friend's message as she awaited to chat with her friend Chaitra.

Shree told Chaitra that she had skipped her tiffin. When Chaitra inquired why she had missed her evening tiffin, Shree answered that she wanted to converse with Chaitra. Shree also told Chaitra that she had just finished her tea and that too in a hurry.
 
Shree Chatting with Chaitra.jpg
Shree Chatting with Chaitra

Even though Chaitra had been a day's friend to Shree, her awe-inspiring and influencing messages prompted Shree to engage in conversation with her.
 
Meaning of difficult words:
 
S.No
Words
Meaning
1.
Awe-inspiring
Very impressive
 2. 
Prompt
To cause something to happen
3.
Adoring Showing great love and admiration
Reference:
State Council of Educational Research and Training (2019). Term-3 English Standard-8. The Mystery of the Cyber Friend(pp. 134-139). Published by the Tamil Nadu Textbook and Educational Services Corporation.