To compress images you will need a program of some sort. There are two distinct varities.
1) Graphic/Image editing software. Examples: Photoshop, Paintshop Pro, MS Paint.
2) Image converting software. Examples: Image Editor Plus, BMP to JPEG converter.
Using image editing software.
Open said image, go to the top right of the screen and choose save as.., then select the file type you wish to save it as and give it a name. This works for the greater majority of image editing software, including MS Paint. Do note however that MS Paint generally does a very poor job.. (It is microsoft, after all!) In photoshop you can do save for web and be more precise in your image compression.
Some programs do a better job than others. Photoshop 6 and 7 both have poor PNG compression tables, but Photoshop CS ( cool does a much, much better job. Ofcourse, photoshop is not legally free beyond its free trial, and is quite expensive, so go with what you can afford. Do searches on google.com or download.com for free/shareware software, and try them out.
http://www.adobe.com/products/photoshop/main.html ~ Photoshop information and trial version download.
http://www.jasc.com/products/paintshoppro/ ~ Paintshop Pro information and trial version download.
http://www.gimp.org/ ~ GIMP image editor. (FREE!)
http://www.irfanview.com/ ~ Irfanview image composer. It's not quite as complicated or sophisticated as the other programs but it will allow you to compress your images easily. (FREE)
http://www.getpaint.net/index2.html ~ PAINT.net, an image editor meant to look and feel like MS Paint but with many more features and tools. (FREE)
Using image converting software.
The way each of these programs work can differ greatly, as well as their quality and ease of use. You?ll just have to find one that works as well as you would like it to. smile
http://www.imageconverterplus.com/google.htm ~ Image Convert Plus information and demo version download. (Adds watermarks to all of your images.)
http://homepages.pathfinder.gr/nsiolios/jpg.html ~ Bitmap to JPEG converter. Only converts bitmaps to jpgs, but is very small and easy to use. Best of all, (FREE)
http://www.imagemagick.org/ - Image Magick information and download. (FREE)
http://www.etrusoft.com/graphic-converter/ Graphic Converter information and download. (FREE)

There are millions of other programs and tools out there to compress and resize your image. However, there will still be people who don?t know how to do this or can?t for one reason or another. If you have any friends, see if they can do it for you. It is important you remember the rules for using signatures on Gaia, and, more than that, to be considerate of other people. Even if the people you?re showing the picture to are using broadband, whatever server/ISP/system is sending/receiving the image is using up more resources for no reason.