I can understand how you find the Wikipedia markup language a bit confusing - I personally think that its markup is one of teh greatest limitations of the entire Wiki concept. But that's another story. :-)

In terms of working with Wikipedia, there are two challenges you face. The first is uploading the photograph or picture, and the second is adding it to a given page.

To upload one or more images, you must be logged in to your Wikipedia account. If you don't have one, create one here: Create a Wikipedia account.

Once you're logged in, you want to go to the special Wikipedia entry Special:Upload (or just enter it in the Wikipedia search box), where you'll see this:

If they're your pictures and you agree with all their requirements of copyright release and related, you can scroll down and:

I recommend you fill in all the fields with as much detail as possible, including specifying that it's your own photograph, as I have done above.

The result is a new page on Wikipedia, like this:

Note the URL as that's what you'll to use for the next part of this process.

Now that it's uploaded, you can add it to the specific Wikipedia entry by editing the page in question, which can be done by clicking on "Edit This Page" on the top tabs:

Then using the following formatting instruction:

You'll want to replace "Example.jpg" with the fully qualified URL of your image, of course.

I'll add my own sailboat picture to the Catalina Yachts Wikipedia entry by clicking on "Edit This Page" (on this page the link's on the bottom of the page. not the top, btw) then added an image tag:

How did I know to add the additional "thumb" and "250px" parameters, etc? By clicking on "edit this page" for a page that had an image presented in the format I desired. Easy! :-)

Sure enough, when you look at the Catalina entry on Wikipedia now, you'll (hopefully) see my photograph included. Pretty darn easy once you figure out all the nuances.