Zguitar, Welcome to Chordie!
Strum patterns are a difficult subject to broach within the limitations of language. Which may be why it is difficult to get help with them. The best teacher is by doing and especially if it can be visually reinforced or introduced via video. I would be looking at anything by justinguitar on you tube, as his stuff is really good, and it is just one guy and his axe in a small studio, communicating in plain language!
But honestly most of us just do our thing and it happens to sound very much like we are following some recipe out of a book somewhere. Strumming is the prime function of the rhythm guitar guy, and he is following and augmenting the percussion and bass line of the tune. So in there with the drummer and bassist is where you are going to find the strum pattern, which is hard to hear as an individual instrument in even a fairly small ensemble. But the beat is your guide.
Sorry I can't give you a better answer, but after so many years of playing it all seems to be automatic... not that it wasn't difficult at first and maybe a little awkward. Just too easy to forget what the early years were like all the time.
The nice thing about Chordie is that we are here to help each other as we can, and I'm sure that more learned minds than mine will come through with other responses that may serve you better. Visit often and you will find a wealth of information at your disposal that can't be replicated anywhere else on the web. People helping people, a community with the common bond of music,
making the world a smaller and friendlier place every day.
Keep making music... it just gets better and better, and again Welcome to Chordie!
Take Care;
Doug