The URL is derived from the title you originally set up. The URL will always be static so this cannot be changed. However, you can change the title as much and as many times as you like. Hubpages assists you with this where they find that some searches have been completed with words that you do not have in your title (Title Tuner on the menu within 'My Account).
Your title should consist of your target keywords as far as possible, and without 'noise' words (as, in, a, the etc).
As you develop your skills in SEO you will develop the skill for title tuning.
It is worth making an effort before setting up your URL also. Not for Google, which does not put great store in this, but for Yahoo and Bing which apparently do.
Anyway, welcome to HP. You should find this a great place to publish your articles. By asking this question it shows that you are on the right track to develop a good base for residual income.