Images, Pictures, Graphics are very important for a website. The old saying (a picture is worth a thousand words) is certainly true on the web, and the proliferation of web technology would never have happened without the graphic content.
Images have the capacity to make the page visually interesting, and to convey information and meaning, to provide visual clues, and to encourage and invite people to read the text. Search Engines however will clearly read the text, and whilst they may catalogue images, they certainly don;t really know how to look at them.
The down side of course is that images add weight and slow down pages. I is generally important not to upload a whole lot more image than you need. There are many tools for making images web ready and web friendly. I am a particular fan of Irfanview. It passes the 3f test – Free, Fast, and Friendly. You can download Irfanview from http://www.irfanview.com an I generally install the plug in as well.
Take a little time to get to know it. If you are only going to use an image at 500 pixels, then re-size it to that size, and save it at about 80% quality to reduce the overall file size. Sometimes reducing the colour depth to 256 colours can make a big difference and then you can gain a lot of speed for virtually no loss in discernibile quality on the web.
Typically the raw images on my camera are around 10 Mb, and as processed jpeg files are around 3 Mb. This is way to big for the web, remembering that the more you put up the more that someone is able to steal, and slow the site down. I sued to have very strict limits, however browsers are a lot faster so it is possible to use bigger files. Most images do not need to be bigger than around 200Mb. The image on this page is around 25Kb. WordPress will do its best to try and make things work for you, however it is clearly better to upload what you really want so you are in control.
For most computers I own I first install antivirus. the nest program I install is Irfanview.