I just had a look at the instructions from the waveshare website and I just found already build kernels and no sources and instructions on how they built the kernel. You may find kernel sources for the wolfson audio card on Github. To get both, the Wolfson Card and the display to work together you need to compile your own kernel based on the sources from wolfson and waveshare. You need to get the changes by waveshare, that they applied to the original Raspbian Kernel and you may start with the already patched kernel sources from wolfson. Compiling on a PI 2 takes some time – but you may crosscompile it on a VM-Ware with the right settings.
Well – this is really not too easy, if you never done this before… sorry that we can’t really help you with this.