As title how to put picture into powerpoint without the background .. Like the pictuer I attached, I wanna put it into my slide presentatons but the white background is kinda ugly ...

Use some tools to convert the image that supports transparent background layer. e.g. GIF files.

Its already a GIF files but still cannot show transparent background ..

You need to change the white layer into transparent layer using the picture/imaging tool. e.g. Photoshop, GIMP, etc.

It is ez.

In your ppt (v2007)
>> click on yr picture
>> click on picture tool
>> click on recolor
>> click on "set transparency color"
>>DONE

convert the picture to be .png (for high resolution) OR .gif (for low resolution & smaller file size)