Here's one way...

I just clicked -Reply-
Then the page flips and I get to the box where I can type.
Below it, gray button box that says -Manage Attachments-
I clicked it
Another window opens up & says -Browse- within it
I clicked it
Window changed to -Choose File To Upload-
I searched my computer where I keep some pics
Chose the pic I wanted
Clicked -Upload-
When done it said -Current Attachments- in it
After that I closed that window
Below window I'm typing, now see it's attached

Simple as pie!

Hope that helps,

iSnipe