Tiggy It is probably because your pics are too big. You make them smaller by using an application that suits your PC or laptop. I only know about Windows so if you have a different operating system, you will have to see what application comes with that.
If you have Windows, there is a very good (and free!) application called Paint.NET which you can download from www.getpaint.net/
You load your picture into that, and from the "Image" menu choose "resize" and then save the picture after you have made it smaller. If you give it a diferent name, you will still have the bigger one if you need it.
On the "Pictures" forum page it says that the maximum size is 50KB. You can see the current size of your picture in Paint.NET as you try different sizes - when you change the number of pixels in width and height it resamples the picture to make it smaller/bigger.
This app is good for editing your picture in other ways too, cropping bits off the side and top and bottom, and so on, and adjusting the auto-level can make a photo look much better if it generally dull and dark. You can experiment with all the adjustments. If you don't like the result, ditch it and start again. If you like it, save it under a different name.