A diary entry is usually an account of a day's events. Hence, your question above seems to be incomplete and unclear.
To answer your question, let us assume that you met an old friend after many years and have been asked to write a diary entry recalling the happy days spent with him.
It was an usual evening after work and I was waiting at the bus stop. Suddenly I see a familiar face standing in the queue. I strain my eyes to look closely at him and realise that he is Rohit, my best friend from school. As I called out to him, he looked at me and reciprocated my feelings. We went to the nearby cafe to catch up on old times. I reminded him of ______________________________________________ (complete the sentence using incidents that you would like to include). He told me about _______________________________________(complete the sentence using incidents that you would like to include). I took him home so that he could meet my parents. Mother was delighted to see him and recollected our childhood days when he would rush to her to escape being spanked by his mother.
It was one of the most happiest days of my life. I hope we can continue to be in touch with each other.