I have journaled for quite a while. I find that writing down my experiences helps me to synthesize the information and process it. I think I would be lost without this outlet for expression. I have had handwritten journals but now I do all on my laptop.
Like others here have said, I use Microsoft Word, no special format, just putting the date and writing as much or as little as I choose. Occasionally, I bring in a journal entry to read to T. Once or twice I have sent him pages from my journal but he likes it better when I read to him face to face!
I have everything in my journal from medication "logs and feelings" to poetry and stories I have written.
Just like therapy, begin where you are!
Sky's the limit.
Peace