In order to compare to the values described here, you should measure yourself properly. That said, there's still some disagreement on what the standard should be, as some datasets use different measurement methods than others. Pay attention to the method used by the dataset you select.
Measuring your erect length should be done when you're fully hard with a ruler (or some other similar measuring tool) along the top of your member slightly pressed onto the pelvic bone (bone-pressed). For datasets that do not use bone-pressed measurements, simply press the ruler against the skin and don't push it any further in. Do not measure by the side or on the bottom. Do not press the ruler under the pubic bone.
If you have a strong/moderate curve to the left or to the right, you can either use a piece of string that goes along the top, following the curve or disregard the curve completely.
Girth (circumference) can be measured using a tailor's tape or a string. There's not a clear consensus if it should be measured along the base, along the middle or along the thickest area, so feel free to use any of those measurements, but do not measure it along the glans/head.