I appreciate your problem because it plagued me for so long. Here is what I did to make posting pics such a pleasure.
Make sure your settings are appropriate. Go to top of forum page and click on "settings". On left hand side of page you will see "General Settings." Click on that and on the page that comes up scroll down to "Miscellaneous Options." Click on the "Enhanced Interface" button where it says "Full WYSIWYG editing." Then scroll down and save changes.
Now you want to resize your pictures in Paint. Open the picture you want and drag into the paint box. Click on image and resize to 25% in both boxes and apply. Go ahead and type in your post. Then click on the tree icon above your post. This will bring up the browse box. Make sure you are in computer not URL. Click on your picture again, click on browse, now right click on picture. It will say Select at the top. Click on Select and the numbers for your pic will appear in the browse box. Click on "upload." If it doesn't say it failed, then it worked. You will see the pic appear in your post. If you have any trouble with this method just pm me and I will walk you through it. Good luck to you.