For a hands on exercise you can try designing a 4-bit to hex 7-segment converter. There is just such an exercise written up on the Computer Science department site of The East Tennessee State University page. All the information you need is in that exercise. Once change: disregard where it talks about your segment; instead design the complete decoder (i.e. to drive all 7 segments). We'll be revisiting this decoder in a future project in this series.
I encourage you to work through the design and, if you can, purchase the required gate chips (I usually go to Digikey for that) and breadboard your solution to see it in action. The digital input and output boards in part 2 of this series can be handy for that.
Alternatively, there are various logic simulators available that you could use to test your design. That said, it's more fun to actually get something physical built and working.