Notebook with GUID partition table

Hello, I just purchased an HP Pavilion G6-2230 Notebook without knowing that it comes with an GUID partition table (GPT)+EFI+Secure Boot. I ave no desire for 100+ primary partitions, no disks over 2.2 TB or similar and i never had a corrupted bios so there s no need for that. However i need an full encrypted Notebook nd guess what most software support only MBR setups. So my question is, since i m a newbie with Notebooks, whats the process here? Do i need to disable EFI+Secure Boot to enter legacy mode so that i can setup my disk and format the system on it and how do i that? Whats the next steps?

Thanks in regards.