How big is the vaginal opening in a virgin? I am one and it is extremely painful for me to insert 2 fingers: i can insert only one finger that too in case I get really ummmmm....lubricated. How will a penis ever go in?

There's no answer to your first question, for a few reasons:

1) The vaginal opening and vagina don't have one "size," in any one given woman. Both expand based on how relaxed and aroused a woman is, and also depending on the size of what is put inside them, and
2) A woman being a virgin -- if, by that, we mean has not engaged in any kind of vaginal sex before -- doesn't necessarily make any difference in the size of the opening since intercourse/vaginal sex doesn't permanently change the genitals in any way,
3) Most women who aren't sexually active don't get sexual healthcare, so per that group specifically, having data on that would be very difficult, and
4) We also have to take into account that some women still have hymens obscuring or partly obscuring that opening, which can make it a little smaller, but again, even some women who have had vaginal intercourse may still have partial hymens.

There really isn't ANY data on the average size of the vaginal opening to be had for women, period, likely because it's just not a useful measurement for any practical purpose, and also because, as I explained, there is no static size of it, at all, and when nothing is inside the vagina, the opening is basically closed.

Two fingers really isn't that much smaller in width than the average penis (the average circumference is around 5 inches), and even when erect, it's a bit more smushy then fingers. But the bigger matter is that if you're feeling pain with those two fingers, and also noting that things are NOT painful when you're aroused and lubricated, you're seeing the central issue here.

In other words, when you're relaxed and aroused, when you're lubricated naturally or using lubricant when you're not, and when you really WANT intercourse, a penis will usually fit just fine, because your body and mind will be in the right space for that to happen and feel good.