Okay, simple enough. I can't write the journal entries for you, but I can get you started in the right direction. I am going to assume that you have read the book. If not, then my recommendation is to write the journal entries as you read the book. Your job is to pretend that you are Brian and write his journal entries. Brian's thoughts are present throughout the story, but at no point does he sit down and write a journal. He has no paper, I guess. You need to write that journal.
I would make entry #1 a prequel to the story. The book starts off with Brian already at the airport getting on the plane. He quickly begins thinking about his parents' recent divorce. The pilot has a heart attack and dies. Journal entry #1 should be before Brian gets to the airport. What is he thinking about? Is he excited about going? Perhaps he harbors some really angry thoughts toward his parents. Perhaps he thinks it is his fault.
The next few chapters are about Brian in massive amounts of pain and in and out of consciousness. It doesn't make sense that he would write a journal entry during that time. But he would likely write a journal entry later about those first 36 hours. Make a short journal entry in which Brian describes the pain that he is in. Make another entry that expresses his thoughts of panic and hopelessness. Make another entry that highlights his decision to move toward surviving no matter what. The author, Paulsen, does a nice job of doing this kind of thing anyway, so take cues from him and try to mirror more of Brian's thoughts in your journal.
That covers four entries so far. Do an entry about his thoughts on why he believes that he will be rescued soon. 5 down, 5 to go.
At one point in the story a plane flies over him, but it doesn't see him. Brian falls into severe depression and contemplates and attempts suicide. For sure make a journal about that. And then for sure make a journal entry about his new attitude about survival after surviving his suicide attempt. 7 entries done.
I've always thought it a bit funny how many times Brian gets attacked by animals in the book. He gets nailed by a porcupine, a skunk, and even gets attacked by a moose. That's just bad luck. Do a journal entry that describes his thoughts about animals. I imagine that he sees them very differently than he did the month before. 8 done.
Make one about his trials and failures while fishing and hunting. 9 done.
Make #10 about his decision to build a raft in order to get the survival kit out of the plane.
And have #11 be his closing thoughts after being rescued.