i suppose the files are zipped up once you unzip you will have a few folders one should be called upload. this is the folder that you upload to your area. dont forget to remain this fill once youve uploaded it or your url for the forums will be example.com/upload
i suppose this version is ipb 2 right?
is its ipb2 then you have to go to www.yoururl.com/folder/install
then you just set the values that it asks for. you may have to chmod some files but it will tell you which ones to do.
hope that helps i not that great at explaining thing in writing but an better hands on