i want to use phpbb forum now the question is for changing the forum skin/ template do i need to have a special prog experience?
if you don't have any mods put in place yet, you shouldn't need any programming experience to add skins. It's usually just a matter of uploading a skin folder into your templates folder, then from your ACP, clicking on <install> under skins management. Very easy to do. PM me if you're having trouble - always happy to help.
but if i will design my template in dw will it working fine. or i should purchase or download some skins which r available on the internet
What's DW? Before going out and purchasing a skin, look at what's available in free skins - just google phpbb skins or phpbb themes - there are literally hundreds out there. phpbb.com and phpbbhacks.com are fantastic sources. If you really want to create your own skin, I'd suggest modding an existing skin - but at this point you WILL need some programming experience as you'll have to change about two dozens files' codes, as well as change an entire CSS sheet.