I should add, that it's a good idea to restrict the size of the image where posting to forums is concerned - an 800 x 600 (or 600 x 800) pixel image size is ideal as it doesn't diminish the clarity too much and also fits in a window without risking the dreaded 'horizontal scrollbar' being displayed in the viewer's browser. I've kept the images as large as possible here, so that people can read the annotation text I've added in each image.
If you are uploading an image to show on a forum such as this and nowhere else, then it would be of benefit to reduce the size of the image prior to uploading to the photo hosting site. The two principal reasons for this are:
1. You're making the most of your free allocation of space, ie you can store more photos
2. You're all good to include the image in your forum post with no further intervention.
The editing capabilities of photo hosting sites are of varying degrees of usefulness. Photobucket's resident editing 'suite', quirky though it is, does provide the user with the ability to resize an image to make it smaller. It is worth remembering, though, that if you use this functionality it will save the resized image alongside the original, so you'll be using even more space unless you specifically delete the larger original.
If you want to keep the original uploaded image, you can post the link to the image in your post, and specify a smaller size locally. To do this, the method of posting is slightly different.
Firstly, choose your image from Photobucket, but instead of copying the 'IMG' code, copy the 'Direct' code:
Then in your forum post, insert the image using the 'insert image' button, filling in the link to the image and the required display size: