On page one, you learned to tune your G string using one of the little buttons that make up the UkeSchool ukulele tuner, which is conveniently located at the top of each and every page here at UkeSchool.com.
Got your G string all sorted out? Do the same thing to other three. No big rush, get used to how to make the string higher, how to make it lower, and how to ease it gently UP into exactly the pitch you're aiming for. Remember, if you leave your mouse over the tuning button on the ukulele tuner after you press it, the note will continue to play, so you can explore at a comfortable pace until you have the hang of it. Tune your C, your E, and finally your A.
Then go back and check - if you tuned the strings very much, they may have pulled on the neck a bit - and then the strings you tuned before will be too loose! You may have to go through all the strings a few times, to get them to stabilize. On brand new, especially cheap ukuleles, you may have to repeat the procedure over and over for a few days until the strings "settle in".
Try not to get frustrated, especially at the start. Eventually, you will be able to tune your ukulele quickly, efficiently, correctly, and out in the real world where there is no ukulele tuner. Some day, but not today, (because your brain needs to think about all this for a while), you should also take our ukulele tuning in the real world lesson in the basic section - you'll learn to do it without the ukulele tuner.
On the one hand, I do recommend tuning, over, and over, and over, for beginning students. You should strive, from the moment you begin playing, to always keep your ukulele in tune. Your ears can become used to the sound of an out-of-tune ukulele. They need to be sensitive to the difference. You need to let them spend as much time as possible hearing a sweet-sounding ukulele. Because that is what you want people to hear when you play - and a big part of what you need to be able to do is to keep it that way.
I should also add, if you really really really feel like the darn thing will simply not stay in tune for more than a few seconds, even though you've brought it into perfect tuning dozens of times already, you may need to have a visit to the page about ukuleles that will not stay in tune.
Next, we're going to learn how to hold a ukulele and strum a chord, and then you'll be able to check and see if it really is in tune!