i want to ganache my entire cake but then pipe buttercream designs around the sides ..will the buttercream adhere to pouring ganache or shud i thicken it for the sides and make a buttercream border on the top a pour the shiny pouring ganache inside the top.becus i want a shiny glossy top .. the buttercream border should hold it in  ??? i know its abit confusing but im sooooo stuckk 

Either way should work well.

Your buttercream will adhere to the sides IF you have chilled your cake first and the ganache is set up. If it's warm at all, it will run down the side. 

I assume that you're looking to do the shiny ganache (pouring it while it's warm) but my personal preference is to let it set up over night at room temp and then use to frost the cake. PM me if you need a great recipe that's full proof!