You can easily update the Android version installed on your phone without using any Computer and do it with your phone over the air (OTA).
Just follow these steps:
1. Open Setting Application
2. Go to "About Device"
3. Find "Software Update"
4. Tap on "Update" and see if there is any new Official Custom ROM for your phone
5. If so, start Updating
* for Samsung Galaxy Devices, you need to have a Samsung Account
* Make sure you have a BackUp
* Choose to install the update only over WiFi, if you don't have unlimited Data