How do I get to North Station in Boston to pick someone up?

We are coming from Portsmouth, New Hampshire. Is there a place to park there? How complicated is it to pick someone up from North Station?

Parking is available right at Norht Station (see link). It isn't complicated at all; in fact, it's easier than South Station. Your party could also take the Amtrak train to Durham or Dover, too.
http://www.mbta.com/schedules_and_maps/s...

For Amtrak service:

http://www.thedowneaster.com/

Parked in Charlestown, there is plenty of parking spots for free on the street. Make sure it is during the day and the Celtics or the Bruins are not playing.

There is a big garage at North Station but it is often full. Another big garage at Government Center 1/8 of a mile away.
Otherwise most of the local streets do have metered spaces.

But how is your pick up arriving at North Station?? Most of the trains and busses that go there are coming from the New Hampshire direction; if your pick-up is as well would it not be more convenient to pick them up some place closer to Portsmouth?

There are several spots where you could park in North Station, there is one immediately in front of the Station - go there early to find a spot. There's also space located behind the restaurant buildings but at times, specially when the Celtics are in town, that get pricey. Take your time, it's a busy area, be careful that when you're looking for parking, in your search, you can easily get off track and end up on the exit ramp to the highway - just be sure to stay on track and around the area. There are always cops in the area, if you get lost feel free to ask; cops will direct you and won't get you lost like in many other states happens. Have fun! I love Portsmouth!