Choose the caption bubble to begin. If you want to upload a custom bubble or alternative image then submit the caption first, then edit the comment and attach a "Place img". Once the image is approved you can use it by editing the caption again.
for some reason I keep reading that as "fag my fat ass," especially when looking at the second to last one. your mileage may vary.
and what the hell is that in the last pic? someone make a C-3PO case mod?