Sometimes, people refrain from making introductions for a number of reasons...they've forgotten the person's name or they are anxious about how to make the introduction properly are two of the primary ones.
There are many articles and tips for learning how to remember names, but, like nearly everything else, it comes down to practice.
As far as knowing how to make an introduction in the first place, it's actually pretty simple:
Name the person of respect (title, age, customer, etc.) first
Name the second person
It does help to also include some basic information and something to connect the people you're introducing, but, overall, it's much easier than one may think. The important thing is...just do it!
Addendum: If you're the one being introduced, always stand to shake hands (with a firm, one-handed handshake) and repeat your name.