Images

Hello,
I am a novice at web design, but am learning quickly. I am trying to create a professional webpage, and want to add graphics to static pages. I have tried using several themes, but the graphics don't show.
I used the < img source = / tag and have checked and triple checked the path. I get the "broken link" box.

Also, I downloaded the adc theme because I really like the transparent .png. I thought I would be able to tweak it to show a different .png...but so far my tweaking has done nothing.

I would really appreciate any help you can give me on adding graphics to the design.

Thanks
Susan