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There isn't much to be said about lucid dreaming that a quick google search can't answer.
What I will say is this, for the common person looking to experience fantasy, lucid dreaming is your chance to play around with the extraordinary.
Using the sigil:
You can use any technique at your disposal.
I will give a simple example of how it can be use.
Either have the sigil printed or open it in an image viewer and place it within three feet of where your head will be resting.
If you using it from a screen, the device must remain on and visible for at least an hour after you fall asleep, this is to ensure that the sigil has ample time to induce you.
Once the induction has been completed the sigil is no longer needed but it is programmed to aid with controlling your dream, so you might want to take that into account.