When wanting to place an image in your blog post, you can simply use the “Upload/Insert” option at the top of the post page..
However, if you want to get creative, or display multiple images in a neat and tidy way on your page, then a gallery plugin might be necessary.
For example, this website uses the NextGEN Gallery plugin to display the images of the templates available to WordPress users.
This plugin will help you create photo albums with multiple galleries underneath it for easy navigation and organisation. It also allows you to display random images in a widget in your sidebar. Overall, it is a great plugin for displaying images on your WordPress blog. Once installed and activated, just choose the Add Gallery option under the Gallery tab on the left sidebar of the dashboard. After uploading images, display the gallery (remember the gallery ID) by including this code in your blog post or page:
[gallery=2] or [album=3]
Although a lot of people like the idea of pulling their flickr or Picasa albums in to display on their blogs, we strongly discourage it if possible since it can decrease your page loading speeds dramatically. If this is a must-do, here are some decent gallery plugin options to look at:
1) Slickr Gallery - Works with your flickr photo galleries.
2) Flickr Gallery - Works with flickr.
3) KB Easy PicasaWeb - Pulls in your Picasa galleries.
4) Photo Exhibit - Works with flickr, Picasa, and Smugmug galleries.
If able to upload and store the images directly to your web hosting account, then these galleries are ones to choose from:
1) NextGEN Gallery - Used on this website to display theme images.
2) Page Flip Image Gallery - Based on the flipping book engine.
3) WP-SimpleViewer - Creates SimpleViewer Flash galleries in WordPress.
4) WP Photo Album - A basic way to create albums in WordPress.
A good plugin for this task is the social bookmarks plugin. To install, follow the instructions above or on the detailed plugin installation page.