Certainly not rude, or ignorant! I didn't even try to check until late in my last pregnancy, when my midwife said the head could be felt through the vaginal wall. That was inspiration to me; I wanted to see if I could feel it, too!
Basically, in a comfortable position, (at this point that's either squatting or sitting on the toilet) you reach inside the vagina with a few fingers. The cervix is at the back (or top, depending on how you're picturing it, and if you're upright or not). This being your first, you may or may not be able to reach it. In multips (women who've had a pregnancy or several before) the cervix is typically down lower, and easier to reach.
I couldn't reach my cervix when I did try to check during my last pregnancy, but I was standing, leg up, and I think that's a tougher position to feel it in, anyway.
Anyway, with a first pregnancy, it'll feel kinda nose-consistancy, as far as firmness goes, or so i've read, with a bit of a dimple in the middle. Effacing is when the cervix starts to soften and pull up, which, again, makes it harder to reach.
If you can reach it, the size of the opening, or os, is how far dilated you are. A fingertip, slightly more than a fingertip is one cm, if you can insert two fingers into the opening, it's about 2 cm, etc.
I've checked several times with this pregnancy, first to get a baseline of what it normally feels like (in a multip the consistancy or hardness is described like the hardness of your lip, as opposed to your nose tip), and recently to note any changes. Since it's harder to reach recently, and softer, I'd say I'm effacing, and from what I can tell from the harder to reach os, I seem to be dilating a bit.
The fact of the matter is that, especially in multips, early effacement and dilation doesn't necessarily mean a whole lot, since a woman can walk around, say, 50% effaced and dilated to 3 cms for weeks before labor. However, I do know that in previous pregnancies, I didn't dilate or efface much until real labor actually kicked in, so I'm hoping that the changes I'm noting now, mean that labor will be shorter and/or easier this time around!