Welcome to the forum , Kramer .
Although there's many 'tips' in for posting images here , my tip goes like this .... (for Windows-based computers) -
Put your image in the 'My Pictures' folder (check the image size , in order to 'stay within' size limits of the forum & edit it to a smaller size , if needed) >
Compose your post & select 'Additional Options' on the 'post reply' or 'post' screen >
Click on the 'browse' button for attachments >
This will open 'My Pictures' .... select the image you want to post & double-click on it >
Select (click on it) the 'Post' button & you're there !
If you're adding an image to a posting that you've already posted , follow the same procedure , except click on the 'save' button when you're done .