To hook up to a 15a outlet all you need is a standard extension cord. A 30a outlet is bigger (kind of like a dryer cord). You will need an 30a to 15a adapter (very cheap) to plug in.
If you have the choice, go for the 15a.
However, the adapter is a good thing to have, as many campsites only have the 30a (for large RVs).
Evan