Depending on how long your relationship lasted, MissKat, I might recommend you avoid dating websites for a while. Especially a place like Plentyoffish where all the crazies you will encounter will make your ex look good in comparison. If all you are looking for is a rebound relationship, just go to a bar and find a decent looking drunk guy.
Be yourself for a while. Get involved with something like the Calgary Sport and Social Club or other community associations and just look to meet
people for a while.