Well if you have adobe photoshop, all you do is open the image in Photoshop(PS) once you have the image onpened Left Click on the Top Border of the Image pane, and select "Image Size", From there you can input whatever size you want to drop the image down to. After the size you are looking for is set, do a "file" and "save as" and save the image as a jpeg. A Box will pop up asking you the "quality" you want to have, and just lower the slider till its under 30k.
Pretty easy once you get used to it!