Open the Phone app by tapping its icon on your home screen or from the application grid. On the bottom row of the Phone app, the first icon on the left will look like a clock. Tapping that will take you to your call history. There are two tabs, one for all calls and one for just missed calls.
In the ‘All‘ list, outgoing calls are denoted by a diagonal green arrow. Simply tap the phone icon to redial a number. For each entry in the lists, tapping on the name (to the left) will open up a full contact history for that number. However, if you just want to quickly dial the number, without reviewing details, tap the phone icon to the right of the entry.