My grandfather was a chef in Italy. It's very important to Italians that someone eats their pasta in the correct way; it's a cultural custom. Food is very important to them. Having said that, the steps are as follows:
1) Hold the spoon and fork so that you're holding them at a slight angle toward each other on the plate like so: 0 IIII
2) Pick up a small amount of pasta with the fork, and place the tips of the fork onto the spoon
3) Twirl the pasta so it's wrapped neatly around the fork (a bit of the end hanging off is fine, it doesn't have to be perfect)
You might try practicing by having some pasta at home first so you're not going for it for the first time in front of everyone. Meeting your girlfriend's family will be stressful enough initially, you don't want to have to worry about how you eat. No worries though, you'll be fine. It's easy...
Born and raised on spaghetti.