I can't take credit for these instructions as someone else posted them and I just saved them down in a Word doc for when I was ready to post. (And, I apologize for not remembering who posted them...it really is exactly what they posted!) But, it worked perfect for me!

How to Post Pics on GardenWeb:
Setup:
1) Go to photobucket.com and open a free account.
2) Follow their instructions for uploading your pics to their site.
3) To enable sharing of the pics and posting on sites like GW, click 'Share' from the menu right below the pic you want. A new window will open.
4) Click 'Get Link Code'
5) Select the first box next to 'HTML for websites and blogs'. Make sure it is the only box selected and click 'save'. (You can also choose to apply this setting to all pics in your album with a link in your album).

Now your pics are enabled for posting on sites like GW!

Posting pic in GW message:
1) Begin the written portion of your posting on GW.
2) When you are ready to add the pics you desire, open a new browser window and log into your photobucket account.
3) Copy the contents of 'html code' box below the desired pic.
4) Go back to your GW posting on your other browser window, place the cursor where you want to pic to appear, right click and select 'paste'.

Your pics will appear in the preview so you can ensure they appear properly before the final submission.

Thank you so much for the detailed instructions, Andi. I wouldn't have figured that out on my own! I will post my message when I get home...:)

Here are some past responses to this question

Here is a link that might be useful: how to post photo files

OK I need it to be even more basic. Help please!

I have the photobucket account and the photos are in there. I cannot seem to figure out how to copy and paste! I have a MAC. Please step me through exactly how to copy and paste the HTML code using the MAC (no mouse). I feel like a total idiot confessing I don't know how to do this . . . . .

I also have a Mac. All I have to do is click in the HTML code box and it automatically copies the proper string.

Which looks like this once pasted into the message box:

You should be able to see that it works when you "Preview" your message.
HTH