Can Not Upload/Insert Product Picture/Image :(

[WanDotShop]

Hi, Everybody..
could someone help me... it to bad without picture into my Online Shop... means that my Online Shop is not Real Shop..

My case is during Upload Product Image... every time i upload it shown "success upload" how ever the picture not appear at lower side...
Only Sub-Categories problem, how ever on Categories and main no problem at all..
I ready read others posting on this issue. But cant find the true answer even that the market given is SOLVED.. but i really dont under stand what should do..due i am not good enough on PHP,Sever, Host setting and so on..

what i know i should change my folder tmp to CHMOD 777... i do it but the result shown 504 command.... i dont know..
someone help me to solve it?
let say that sever hosting not given permission..how should i do with my self to make the permission ON..
due i am not directly can edit at sever but i can ask someone to do it due that sever belong by my family..
what step need? what the setting needs?
could someone given me step by step...TQ