how do you flip a photo image over using Gimp?

Question

I mean not the "flip-rotate" feature, but in order to have the image backwards so you can make a t-shirt. thanks

Answer 1

That function is called mirror or flip horizontally.
http://gimp-savvy.com/BOOK/node32.html#SECTION001063000000000000000
Here is the Gimp tutorial on how to do it. Look for the pelican, Figure 2.22: Using the Flip tool

Answer 2

Open a photo in GIMP. Change the canvas size using Image > Canvas Size > double the width of the photo, Click and drag the photo over to the right side of the canvas. Click resize. Use the text tool to type some text over the photo. That's the front of the card done. Click Image > Duplicate. Now you have a new image - this will form the back of the card. Click and drag a guide from the ruler at the left side, and drop it at the middle edge of the photo. This guide will show the centre fold. Select the photo layer in the layers dialog. fill the entire layer with White by clicking Edit > Fill with BG colour. Delete the text layer. Now choose the text tool again, and add some text to the right side of the image - this will be the greeting inside the card. That's the back done. Print off the first side on some thick photo paper. Fold it into a card - trim if necessary. Print off the back on plain paper, fold it and trim if necessary, this forms the insert. Glue it in along the spine, stick the insert into the card. Tadah!!!