learning photoshop ryt now, how do i add shadows that blend with

>>2923650
You're trying to put a photo with an ambient light setup into a photo with strong directional light (plus atmospheric perspective). Basically you'd need to do an unreasonable amount of work to get them to mesh well, like essentially painting in all the shadows correctly.

Try to use photos that match lighting already, then it is easier to combine them and all you need really is to cleanly cut out one photo and then maybe use some adjustment layers and colour grading to get them to match closer, maybe also add in some simple occlusion or cast shadow with a multiply layer. What you are doing will be a lot harder since the photos don't match at all.