Kitty,
Here's a quick and dirty tutorial:
You'll need some software to resize the images for you. Pretty much all photo editing software can so such things. There will usually be an Image Size option on one of the menus (sometime under edit, sometimes Image, sometimes Option). -- search the program's help for
"image size" or something related and it should help guide you.
Usually all that is need is to open the Image Size dialog box and make the change there. Some programs will let you type in a percentage that you want, like 70% of the original size, others you type in a new height and width. One major caveat: if you type in a new height and width, you need to change them an equal
percentage -- not number of pixels or millimeters or any other size measurement -- or else your picture becomes distorted. Most programs that let you type in a new width and height have a feature that allows you to “lock” the aspect ratio so if you change one value (say the width) it changes the other value an equal percentage so the picture doesn’t become distorted.
As for your question as to “What is a pixel” – a pixel is one PICture ELement. You can go to
www.whatis.com to get a more detailed definition and explanation. Do a search for pixel (or any other Computer term you want to know about.)
I know that’s only an overview of things, but it should hopefully get you started. Key thing – use your software’s help and search it as needed. Also do online searches. There are lots of sites that have Web Mastering 101 type stuff, many of which will discuss images.
Good Luck!