Look at the data sheet for the display you are using. It will tell you what the pinout is (what each pin does). Most 7-segment displays have 10 pins: 7 for the digit segments, one for the decimal point, one common (cathode or anode) and one unused (or could be a 2nd common pin).
Then, draw a diagram on a piece of paper so you can work out what segments need to be lit up. Start with one "digit". Wire those segments' pins through resistors to your power supply, connect the common pin to ground (if the display is common cathode, or the + side if common anode), and see what you get. If the right segments light up, you're good. If not, fix your mistakes and try again. Repeat for each additional digit.
To make things simple, use separate single-digit displays rather than a multi-digit display. Most multi-digit displays share the segment pins and have a separate common pin for each digit, meaning you'd have to multiplex the display to display different characters on each digit.
Then,