To make it simple, there are #2 ideas to pattern racking.
Either for yourself, assuming your making balls and want an easy pattern to get out...
Or....
For your opponent to make it difficult to get out. We used to call these travelers racks

where the idea is that each sequential ball ends up at opposite ends of the table so you have to constantly get shape back and forth the whole rack.
Their are many patterns posted around but patterns are easy to figure out. Just rack some balls in order thru the rack, break a few and make note of where the balls 'generally' end up. Now you know roughly where each spot in the rack ends up on the table after a break. Now you just rack the balls in the spots of the rack you want them to end up in the table. Its not rocket science and its not at all anything new.
So thats the jist. Hope it helps.
For the record most people HATE the idea of pattern racking so you might want to keep it quiet that your trying to learn it.