thanks very much, that me respond sentence by sentence

>Your camera has to have a full manual mode (usually marked as M) for you to be able to control aperture.

yes, i have full manual mode. i can control aperture.

>Some cameras also have an aperture proiority setting that allows you to set the aperture you want and the camera adjusts the exposure speed accordingly.

yes, my camera can do that too. either set aperture priority, or set aperture first and adjuster shutter speed.

my camera cannon A540, can not do background blur. i just purchase my camera 1 month after i came to travel forum. so it is only 5 month old. if to get another compact camera, it will be duplicated. i am not hurry to buy SLR, but i am keeping that in mind. i guess that i was affected by photography forum. hahaha...