Are you sure its a valid format? Best bet is to go with a jpeg. Also yes, when you make a new post (reply) then at the bottom where it has the box and the browse beside it, click that and navigate to the pic. Could possibly be the wrong format, cookies disabled (eh, maybe), security on your system, or your through some kinda router or hub and you need to foreward certain ports
. Hope you get it working though seeing I want to see your progress, i love swords, katanas especially.