Posting pictures on Blogger isn't too difficult. It requires 2 steps. First, the pictures must be stored online somewhere. Second you must tell the blog where to get the pictures.

Unfortunately Blogger does not directly provide "image hosting" so you need to have them stored online somewhere else. Usually if you have an email account your provider gives you some storage space for putting files (pictures, webpages, etc.)

Once you have an image online, you can include them in your blog by using what is called an HTML tag. It has the format:

<img src="http://www.example.com/mypicture.jpg">

(Just replace the www.example.com/mypicture.jpg with the location and filename of your picture.)

For example, I have pictures on my comcast account stored. Here's one that shows our hard-working dog, Eddie:

My directory that I've set up for storing my photos is http://home.comcast.net/~j64thomas/blogimages and the file name for this picture is is sleepineddie.jpg. To post this in a blog, I type
<img src="http://home.comcast.net/~j64thomas/blogimages/sleepineddie.jpg">
and then when it is posted to our family blog, the blog will grab the picture from my online storage location.

According to blogger.com, Windows users can also use the Hello BloggerBot to post pictures directly to their blogs. Mac users (and anybody else, for that matter!) can use Flickr to photoblog; see this article for details. (Sorry I've not used these so I don't know how easy or hard they are)

Hope this isn't too confusing, but feel free to experiment a bit and let me know if you have more questions.