Thank you for elucidating more upon your experience, and, again, welcome 
To answer the questions you asked:
No, you do not need to carve the demon’s seal in the metal corresponding to its astrological attributions. You can, of course, but these days, most magicians simply draw them on clean paper (our modern version of virgin parchment).
You can find a lot of information on invoking demons in demonolatry, a religious practice that worships demons as the Demonic Divine. S. Connolly has authored many books you may find useful.
What most of us here on the forum do is evoke demons. The traditional ceremonial magick definitions of evocation and invocation are that evocation is the calling forth of a spirit to take form before you, and invocation is the summoning of a spirit, within you, to take on its energy or traits.
Gods have traditionally been invoked, and demons have been traditionally evoked.
As for instructions, try this: