I'm not too sure how you're able to access the internet while incarcerated, but for maximum safety, I wouldn't suggest accessing the ToZ website or even these forums too often.
If you've already read about a few basic meditations, then start with those like aura cleaning, the Foundation Meditation, Void Meditation and breathing techniques. Even with these meditations though, be extremely safe about not attracting attention to yourself. Meditate when you can assure you won't be disturbed and keep a low profile with this.
As far as performing the Dedication Ritual, this is definitely not advised and you're better off performing this inside your Astral Temple. This will take time though and there's no pressure to doing this anytime soon. Just follow the meditations in the ToZ, with absolute safety and awareness of your environment, and the Astral Dedication will be easier for you to do.