Now it's time to start writing your entries! This is the fun part, the main reason you are doing this diary in the first place.
Design the page and decide how you want it laid out. Add the links to your other pages and make the page look the way you want it to. Add the links to your entry from other pages so it can be found.
Think about how you want to go about writing it. Do you want to be bold and honest or do you want to become a fictional character? Will you tell your friends about it? Will you use your name?
Create a template page. A template page is a page that is all set up to start writing but is not yet written on. The design is there, the layout is there, the links are there, but the writing is not there. This way whenever you are ready to write a new entry you don't have to do the coding all over again. Just open your template and rename it for the new day.
Now start writing. Write your first entry. Add pictures and graphics where you want them. Ask for feedback from your readers if you want to. Post your entry and see what happens.
Post your diaries here! Let others see what you have done so far and get opinions and criticisms. Getting advice from others is the best way to create a great site.