how do I get cubase 8 le to recognise my softsynths windows

Hi all excuse my limited knowledge, albeit I am an experienced musician of many years I have only just started to set up recording functions and decided on Cubase I have arturia, omnispshere, and some Kontact 5 spent loads of cash but cannot get them to work on Cubase. I think its something to do with the dll file path but I cannot find it at all… it is doing my head in at the mo trying to get this sorted. I have reinstalled Cubase as I think that I had deleted the file path for the soft synths that did initially load but now they are not even showing. I am struggling and would appreciate any advice. I am on windows 10 and struggling to find anything on you tube. thanks in advance.