Step 1: Format of an Informal Letter: The letter follows the informal format with the sender's address, date, salutation, body, complimentary close, and sender's name.
Step 2: Tone and Language: The tone is warm, caring, and advisory, suitable for a letter to a younger sibling. It is encouraging rather than scolding.
Step 3: Content: The letter starts with a pleasant opening, states the reason for writing clearly, gives constructive advice (balance studies and play), expresses confidence in the brother's abilities, and ends with an offer of support.