You should not rely on nor look for tutorials.Context switching is just changing the virtual address space (i.e. page directories/pdpts) and the content of the registers, basically.
There can be some issues with
specific registers but i don't believe they apply to x64.
Context switching is just that. Saving current state in a structure somewhere and restoring state from another structure.
Why are you looking for a tutorial ?
By 'context switching', do you mean 'scheduling' ? Do you mean more generally 'multitasking' ?