You can work out the concentration of H+ ions (denoted as [H+]) easily on a calculator if you know the pH, which you do. The easiest way to work out [H+] is to do \(10^{-pH}\). In your case, the maths here would be \(10^{-3.8}\), which gets you an answer of 1.58x\(10^{-4}\), or 0.000158. For 6.2 it would be \(10^{-6.2}\), which gives you 6.31x\(10^{7}\), or 0.00000063. As you can see, the concentration of H+ ions is greater in pH 3.8.
To put it simply, the [H+] decreases the higher up the pH scale you go, and increases as you go lower, but now you know the maths to work it out for yourself too.
