Default Help installing 3rd party apps on Nook HD+

I just bought a Nook HD+ and I am looking to load 3rd party apps and all of the research I have been doing shows how to do it in older versions. Alll of the suggestions I have been doing to access the "allow 3rd party apps" menu have been for naught. Can some one please direct me on how to do this or to a current thread on how to do this. I would very much appreciate it. I am sorry if there is a current tutorial that I have not found but I appreciate any assistance. Thank you very much