You have to resize your pics pretty small to attach them, and there are programms for that available on the net, or you might have already. It's a bit hard to explain without knowing what you have.
The easiest thing I reckon, is making a photobucket account and putting your pics up there.
www.photobucket.com Just follow the instructions to make your account and it's easier than uploading your pics to the aps gallery, and it's free.
And then you can link to the pic in your reply, like you do in the gallery using the img tags.
When you have uploaded the pic onto your photobucket acccount, click on it, so it brings up the pic at full size. Then right click it and go down to 'properties'. The url will come up in the information about the pic, called 'address . You then copy the information (t...rnet viewing size for you automatically too!!