I've been working for one year. Can I apply for grad school in CS in Canada?
Your best bet would be to get in contact with a specific professor who is an active researcher in an area of CS in which you would like to complete a Masters degree. If you find a supervisor who is keen to advise you (which you will need, anyway), he/she can help you negotiate the university admission process. 

However, be forewarned. Many professors receive a lot of unsolicited emails from candidate students and are unlikely to respond. You need to make it very clear from first contact why it would be in his/her interest to supervise you, in particular.