I have no links to offer you , partly because I am on mobile at the moment and also because that there is quite a fair bit of information concerning meditation that it would be rather impractical for me to find sites to list them. Furthermore , what I have learned from meditation are largely based on books , talks and lessons by various monks and henceforth.
I suggest it would be best for you to look for sources of information elsewhere.
Meditation is a fairly large topic and many believe by doing a few common technique practices , they have mastered it , though there is so much more. Though that is usually sufficient for spellcasting