Getting nice background blur with a compact digicam is tricky, the small sensor size gives a much larger depth of field (the area of the picture in focus) than the larger sensors on SLRs. Unfortunately this is the laws of physics at work and all you can do is work round it.
The Ixus 50 has a manual mode which will allow you to set the aperture yourself - it needs to be wide open (small f number) for the smallest depth of field. That means you could need quite a high shutter speed for a good exposure and a bright day may mean the required shutter speed is faster than the camera is capable of.
With that set to get the minimum DoF you need to be quite close to the subject. I ran some numbers through an online DoF calculator and at full tele zoom, an aperture of f2.8 and a subject distance of 3 feet the DoF is about 3-4 inches. This should be just about perfect for flower shots etc.
Obviously there's some trial and error involved but don't be afraid to experiment, it's not costing you anything.