Adding images to posts

Sorry for the newbie question, but I’m having a lot of trouble adding uploaded images to my blog posts. I read the documentation on codex, but it was no help.

I tried uploading my image to the /wp-admin/images folder and also to /wp-content/themes/425/images folder. I tried both and when I used the image tag in the post and used the url for the image, nothing appeared. Did I load the image into the wrong folder? Did I enter the url incorrectly?
Any help would be appreciated.

thanks