How do you change pixel size?

i need to change a picture on picasa 3 or paint to 480 x 272 please helpHow do you change pixel size?
It isn't the pixel size you want to change but the image size.How do you change pixel size?
Open the picture in Paint, click on Image, at the top left then select Stretch/ Skew, this alters the '%' , by trial and error you could reduce/ enlarge the picture until in Attributes you get the pixels you want or near enough, then I think you Save as, to that size, have fun....



Will look further....found this, here's hopeing..

http://picasa-readme.blogspot.com/
in paint.net, you go to ';image'; on the tool bar and select ';resize';.