What does minor thrush on tongue look like?

Multiple types. There are at least two forms-proliferative with a white removable coating & atrophic with a distinct border & redness. Both need treatment by a qualified practitioner.
White-Yellow Patches. Trush is usually a whitish-yellowish patch (or patches) on your tongue. With a little effort, you can usually rub them off, &it might bleed a bit beneath. It can also affect other areas of your mouth. You have to be very careful that it doesn't spread into your throat and lungs, which is very dangerous. So, see a dentist and get some medication right away. And, make sure it's not something else.