Keeping a diary in the technological age is as simple as in the real word pick a diary(piece of software/app) and start writing. The diary of choice being as much a reflection of taste and personality as the diary you would buy form the stationary shop.The main difference on the web is the possible voyeuristic audience is no longer limited to family and friends. It can be with a little know how of course limited to your self but with a lack of knowledge it can be left for the entire world to read. To secure it, unlike hiding your journal under the bed. You need to set choose the write medium and then learn their rules. But it can be made far more secure in public view. Almost like leaving it on the coffee table in the coffee shop but with in a see through case and set in place every one knows where it is and can see it as they pass by but no one can read it should you choose.
A excellent article on the flavour and verity of blogs and subjects available can be found at http://modernl.com/article/the-blogging-spectrum. While your choice of medium is compared http://webupon.com/blogging/top-31-free-blogging-websites-the-ultimate-list/
Its the medium of blogging thats my main focus today, from Live journal which in ways feels like Facebooks older cousin, to Facebook which is more akin to the journal under your bed except every so often they turn your bed upside down on the street. Wordpress and Blogspot which are the cool kids journal shops, depending on your style fashion and nerd status.
I can go on like this all day about various blogging sites and software and their look, feel, and approach.
I think it better you look at the two articles above as they have done this for me.
