How do you upgrade Android OS on a Samsung?

Many phones will update automatically, once the Android OS (Operating System) update is available for your model. Many won't, though. The first thing to try, when upgrading your Android, is to go into your phone's settings, and select About Phone, then System Updates. If you get a message, "Your system is currently up to date," continue reading. Otherwise, follow the steps on your phone and you'll be updated!

At this point, verify that there actually is an update available for your phone. Either google it or tell me, in a comment, what phone model you have and I'll let you know what the latest version of Android is for your phone. Assuming there is a newer version of Android, here's how to get it.

On your phone, you should have an app called Kies. There is also a computer version of that program, for Windows or Mac. Download it here, if you don't already have it. Just opening the page in your browser (like the app tells you to do) won't cut it... you need to actually download Kies, from that page. 

Now plug your phone into your computer. Kies should recognize it automatically. If you want to save your phone info (pictures, music, contacts...) then open the Back Up/Restore tab, and follow the instructions there. Now click Firmware Upgrade and Initialization, in the Tools tab. Follow the steps there, and hopefully Kies will find your upgrade. If it also tells you that your version of Android is up to date, then continue reading.

Unplug your phone, and navigate to Firmware Upgrade and Initialization again, on your computer. The first step you'll need to do here is enter your phone's model number, which is something like SGH-I900 (make sure you do all caps, or it won't recognize it), and then your phone's serial number, which can be found in About Phone under Settings, or else under your battery, in the back of the phone. Continue through the process until the install is complete, on your computer. Now you need to put your phone in download mode, which you do by turning the phone off, then holding down both volume buttons at the same time as you plug the phone back into your computer. From here, everything should finish automatically. Your phone will show a message about downloading, and warn you not to turn off target. Soon your phone will restart with a beautiful new interface, and you will go through the original set-up process again. If you backed your phone up, now pull it up in Kies to restore the backed up version, which will put the info back on, but will keep the new Android version.

This is a bit complicated, but very easy to do, step-by-step. If you run into any trouble, let me know and we'll see about getting your Android updated.