How do you type on my laptop and keep it secret?

The best way is to never type it at all, as bleak as that sounds. Short of that, there are many precautions you can take. An information removal program and a hard drive wiper are a couple of tools you can use. After you delete any traces of whatever information, you would wipe the free spaces so the information can never be retrieved. Windows delete is not enough. You can also use programs like ccleaner which help delete cookies, browser index files, MRU entries, etc. It is always helpful to run spyware and virus programs to make sure there is nothing installed that could allow others to eavesdrop.