To get to NYC on a train from Manassas, you have to go to Union Station in D.C. and get on another train. The times stated by prsahni are probably accurate, unless the train to NYC has stops.

If your taking Amtrak you can get a parking pass from the office in the station

I'm fairly new to the area but I take the VRE train weekly into DC. If you get on in Manassas, there are two stations, one is at Broad Run near the Manassas airport which is the end of the line. The other one is in Old Town Manassas and is the one I use. This is the second stop going into DC. As mentioned in a previous post, there is also a Manassas Park station (third one in) so please don't get them confused. Not sure about the Broad Run and Manassas Park stations but the Old Town Manassas station is also a stop for the Amtrak trains. This Virginia Railway Express (VRE) line is the Manassas line and will take you into Union Station in DC which is the end of the line. You can buy tickets and see schedules online. Google Virginia Railway Express and the website will come up (TripAdvisor won't let me leave the link in my answer). They have a mobile app and you can purchase the tickets with your smart phone and they're stored directly on your phone. You can buy tickets one way and/or round trip by zone. If you're going from Manassas into DC your tickets should be from zone 6 to zone 1 or vice versa. You can also buy paper tickets at the station thru vending machines and/or at set places the website can tell you. You must buy your ticket and validate it prior to boarding the train. Paper tickets you can validate at machines at the station. Online/smart phone tickets can be validated electronically on your phone when you opt to use them. Personally I do it electronically which is easier for me. There are two lines for the VRE. The Manassas line is the one you'd take from this area. The other line is the Fredricksburg line and it does not come this way. Both lines stop at all stations starting at Alexandria into DC/Union Station. Beyond those stops, the trains split so when boarding the train in DC you will need to look for the tracks the Manassas trains are on (they have them listed on the board and on the signage on the side of the trains). Ticket prices will vary as you can get a single ticket (one way) up to ten (five round trips). I believe (off the top of my head) a one way trip is $9.50 so $19 round trip. As this is a commuter train, they don't have full luggage racks or a baggage car but you could take a carry on bag, work bags, etc. with you. You could take a full size bag as well I'd guess but it might be awkward. They do have places for you to put your bags though. If you will be using the train for commuting purposes, contract the city of Manassas for a parking pass if you plan on parking at the station. The pass is free for Manassas residents and you can complete the application online. If you're not a Manassas resident, I'm not sure if there is a cost involved. The pass is good for one year. If this is just a one time thing/every so often.....no worries :-) The VRE has several cars with toilets (sometimes you just have to go) and they have a quiet car (no loud music, phone conversations, talking). While I've seen people drinking on the train (ie. morning coffee, sodas, etc.), I've never seen anyone eating on the train (doesn't mean you can't though). Alot of information.....I know, but I hope this helps you.

The Manassas station is served by the VRE (commuter line) which starts around 5am from the Manassas airport ending in Union Station in DC, running approximately every half an hour. For better schedule times please check their website. AMTRAK is the other rail service, have no idea of their schedule, also check their website.