Browser fitting and javascript?

Hello wordpress community I’m new to the wordpress platform so all support is thankful. My last and first issue was solved quite quickly so I realize how helpful you all are. My issue is I view my domain on a 27 inch iMAC. Everything is smooth i see my wallpaper and all perfect.. issue is depending on screen size of person computer/laptop the view is always different. Is there a way I can have it fit to it’s best ability. I downloaded an app called php java browser detection but it truly did nothing. Also when I view the site on my iPAD it looks a mess. my domains are
http://www.dondriquethemayor.com
http://www.duceman.com