how do you make it smaller?
It depends on your own software or camera's included software. If you are not familiar with making picts smaller on your computer, you probably need to check out your camera's software manual or look for some software that will crop and reduce the size of the pict. Each program has its own particular set of commands/instructions for doing what you are asking. For that, you will need to read their manuals or instructions.
I use Photoshop and I don't think you would want to put out the money or time to learn PS just to post picts. Since I've had and used this program for 14 years, I am not familar with other programs "how to".