What software are you using to create the image? Make sure you save the file as a transparent PNG formatHey, so I thought I would give this a go. I started reading the instructions on teepublic on the rules on your image and it got very confusing. I'm going to keep things simple to start with and just have a simple image and text all in one colour.
One thing I am finding confusing is that the background of the image is white as the actual text obviously doesn't cover the whole thing, but when I click on upload and look at it on a t-shirt, it looks like a big white box with my text on. Should I have changed a preference somewhere?