Please tell me... LOL

One way:

At the bottom of a post/reply there is a box area labeled Upload Attachment. Inside it is a Browse button you should use to select the file on your computer. Once that is done click the Add the File button beside the comment box. You will see the file uploading and if all is well will be there when you submit. If the file size is excessive you will receive a notification to that effect, prompting you to shrink the file using whatever graphic software you have. What's the size limit? Don't remember but IIRC it is less than 2M. IF you pre-shrink the file to 1M I do not think you will have problems.

There's more than one way to "skin this cat":

I use Google's free image management system, called Picasa.

From Picasa I e-mail an image to myself (It is automatically re-sized for the e-mail.). I open the e-mail and save the image to a purposely created "junk images" folder. When I want to post an image in a reply I click the browse button and the "junk images" folder is the first in the list of folders. I open the folder, find the image I just saved, and left click on it. I then click "add the file".

It takes less time to do the above than it did to type the paragraph.