Hit the button "New Topic", to create a new topic. You will be taken to a new page where you can start writing your first post. In the subject field, write the name of your journal e.g. Immy's Journal of T20's etc.
Use this first post to introduce yourself, give a brief history of your trading and yourself.
When you are ready hit the Submit button.
Also, note that if you wanted to preview the post before submitting you can do that too by hitting the preview button. You can also use the Save draft button if you want to save this post and come back to it later.
Below this panel of buttons, you should see three tabs. Options, Attachments and Poll creation. Use the Attachments tab to upload and attach any image file (.png, .jpg etc) or pdf of doc (Microsoft Word) file you want to attach. e.g. if you have your trading plan ready, use this tab to attach that file to this post.
Once files are uploaded hit the Submit button.
Congratulations you've created your first topic which will be your Journal.