Hi hsshss,
What I do to post images, is...
A ) I have the images I have just taken on the floppy disc ( yes, I know, no one uses THOSE any more! But the same would apply for 'stick' image memory or whatever one's Camera happens to have, or one plugs the Camera in to the Computer ) and, then, right above the Box in which we compose our missives, there are various little 'Icons' which are in a row - 4th from the right, is the one which one clicks to insert an image.
Click on it, and it opens a little mini-window which then allows one to 'Select files', which of course is to go after the image according to it's location, and, to highlight it or elect it, so that it then will be selected, and, will appear in the Post.
Or...
B ) If I have put an image in to some folder or other on or in my Computer, then I would elect it 'there' in the folder it happens to be in, via the mini-window's 'Select Files' operation.
Or..
C ) If the image I am after is one I have put on to some Web Site Image Storage place, ( like say Photobucket, Fotki, or whatever ) there will be a method which is part of how that Web Site does things, a method to elect one's image for posting it in to a Forum, and, one will copy a Code for that, where one then pastes the Code into the Text Box in which we normally compose our missives or posts. And one's image then shows up in one's Post, by doing that.
If any of this sounds confusing, it is only because I did a crappy job of trying to explain. It is quite easy, once one has figured it out! Lol...