OK. I'm going to do a basic repeat of the OPs post in the hope that it will help anyone who is still confused. It may also help any of you who choose to use Imageshack for online photo storage.
Personally I use Imageshack (the free version) for storing on line the pics I want to post. It's all I use it for really. The only gripe I have with Imageshack is that some pics, esp. older ones, seem to be temporarily unavailable periodically.
I use Irfanview, another free downloadable program, as my usual viewer and manipulator of pics. It's a pretty simple and basic little program but does nearly everything that I want.
Before I upload to Imageshack, I use Irfanview to re-size the pics. I find it easier to do it at that point.
For nearly all pics I'm posting on the forum I re-size to 640x480 which is quite big enough, (all the following pics are that size) or for a bigger pic, 800x600. Any bigger than that won't fit on a lot of screens. Imageshack also provides you with the opportunity to re-size as part of the upload process. A recently added feature.
The following looks a bit long and complicated, but it is not in fact.
Uploading an image and posting as part of the process.After opening Imageshack in your browser if you push the
Media Upload button, you get this window;

After clicking
Browse I've selected an image and used the Imageshack tool to re-size it.

Once uploaded, a small version of the image is displayed in the upper left of the screen;

Over to the right of this is the button
Continue to the image links
When you push it you get this;

You can see that down in the "Links to share your image" section I have clicked in the box labeled "Forum Code"
All I have to do then is click the
Copy button on my browser, and, in the message composition box on the forum, click
Paste.
In the composition box it will look like this;

But I choose to
Backspace over the bottom line that begins with "Uploaded with" as it is just Imageshack advertising. It then looks like this;

When you go to "Preview" or post your message, there is your picture!
Here it is by the way. It's the 2013 Mogan 3 wheeler. Yes, they are making them again and the base model will only cost you 25000 Pounds Stirling!!! :o
Posting a pic already stored on Imageshack.A pretty similar process with out all the uploading. When you open your Imageshack page, your pics are displayed like this;

The pics have a series of icons alongside each thumbnail

Clicking the top on, the blue 'i' takes you to the share' window;

I 'un-tick' the box for 'Include Details' which leaves this;

From there it is just a matter of Clicking in the 'Forums' box, and copying and pasting as before.
Here is the pic. It is the refurbished Endeavour.

Done! And what an exercise making this post turned out to be. I hope it is of some help to someone. If not, it was an interesting exercise for me. I obviously have too much time on my hands, probably as a result of being temporarily unemployed. (again... sigh)