In Safari you mean Sqad? If so, does the link open a new tab or in the tab you are already in, if the latter then just tap the 'back' arrow at the top left of the screen, if a new tab then just just select the original tab at the top of the screen. If you mean a link from an email though, either double click the home button to bring up the list of running apps and tap on the mail icon or if you have multitasking gestures enable in 'settings', 'general' just swipe the screen left or right with four or five fingers to switch between apps (this assumes you have IOS 5 installed)