importing entries from an old website

So before I decided to use the nice and streamlined WordPress, my website used it’s own “blogging” software which I coded myself with PHP/MySQL. My question is, is there any way I can back up these old entries from my database and somehow import them into WordPress’s database. I have WordPress’s tables and my own tables still on my website. On my own created table, all my entires have seperate rows for the title of the post, the post itself, the date, and the user. If it is possible I have no idea how I can go about doing this.