With what you are doing, you are already halfway there.
You have access in Flickr to the Large photo, correct. You should be able to right click on it and "Copy Image Location" which is what you already do now with medium size photos, correct? Now, instead of using the tag you type or using the "Insert Image" button that looks like a picture with the green plus circle, [COLOR="Red"]click the Earth button with the link[/COLOR]. Then paste the location from the large image in there. This should do all the work to make it look like a web address and you will actually see the web address twice, only the second one is already highlighted for you. Don't touch that.
Now, do as you did before with the medium photo. Right click on it and "Copy Image Location" and click the "Insert Image" button and paste the medium image web address in there. Hit OK and this should automatically have placed the [IMG] tags and everything exactly where the highlighted portion of the second web address was. And that's all you need to do.
[ URL="http://farm7.staticflickr.com/6057/6373130295_c6d3f8b892_b.jpg"][ IMG]http://farm7.staticflickr.com/6057/6373130295_c6d3f8b892_z.jpg[ /IMG][ /URL]
The code should look exactly like this except for the space after each [ what I had to add so it wouldn't post the picture. Hope this makes sense.[/QUOTE]
what is the EARTH BUTTON?