a few issues I cant work out…

1) My logo is displaying really big when viewed in laptop, but fine on tablet and mobile screen preview...can I fix this? 2) I cannot work out how to change the featured slider images to show images I have uploaded... 3) Home page featured content - where/how do I change/add the images and text shown on the default for the theme? I like the way its et out and just want to upload my own images and text but cannot find how to do it.. thanks in advance :)