What I have, personally, done in this kind of situation is take a close look at their character sheets, what can they do, what are they good at, and write an 'easy mode' adventure where they get a chance to use each of their abilities.
Once they come to a point and don't instinctively realize what they're supposed to do, gently ask the relevant player if they can do anything about the situation. Beyond that, don't forget to include basics regarding your GMing style.
For example, if you use a lot of traps, start with a few light and relatively harmless traps. Enough to wake them up to the idea that not everything that can harm them can be seen, should help them get them used to searching.
You can also show off some tactics that can be useful for anyone by making the monsters use it. Aid another mid-fight, flanking, readying actions, et cetera. Make sure to let the players know that those are things anyone can do.
It's fine to be a bit railroady during such a tutorial adventure, especially with newer players, but don't forget to include the roleplaying parts as well.
My group uses a private Google+ community to organise the games, and G+ alongside Roll20 to play the games. We play entirely online on a weekly basis, mainly because we're all about the same age and have small children and families, so it's difficult to get together for a face to face game.
For D&D 5th Ed you're pretty spoiled for choice, but when it all boils down the best two options are this:
Roll20, either in conjunction with G+ or on it's own. You can create an account and run your campaign through it for free, and the biggest pro (in my opinion) was the ease of use when it integrates with G+. Most everyone has a google account these days, so they also have a G+ account whether they know it or not. Once you've created your game in Roll20, you can choose to launch it in a g+ hangout.
Once you've done that for the first time, whenever you launch a G+ hangout the Roll20 app will be present, and you can launch it and select your campaign from within the hangout. Running the game each week becomes as simple as scheduling a G+ hangout event and showing up - the players don't even need Roll20 accounts, they just click the hangout invite link and game on. The D&D 5e character sheet for Roll20 seems pretty excellent too, with some dice rolling automation built into it. We're taking it for a test run soon hopefully.
The other main option right now, though it can get pricy, is Fantasy Grounds. It's not as simple for the players as Roll20 (which is, as i've said, just a link click), but if they're willing to install the program (available on Steam now as well), Fantasy Grounds is now the official online tool for D&D 5th, in partnership with Wizards of the Coast. It has excellent integration with the rules system and character sheets, as well as supporting hero lab. Some friends of mine swear by it, though it is a bit more complicated to get set up and running.
Both solutions support full voice, and I know Roll20 supports full video both in the app itself and through hangouts, as well as an online tabletop for maps, images, handouts and whatever else you like. This made it a lot easier for us to retain that "social tabletop" feeling, despite playing entirely remote. Using a large enough screen and a good set of speakers and microphone, you could play partial remote (with only a few players remote) or even with everyone in the room and disabling the voice and video altogether if you wanted.
Either way, if you do plan on getting in to running your games online through virtual tabletops, Google+ is your friend! There is a massive community of people there who will be more than happy to lend any assistance required.
Personally, I run a community geared at assisting people to set up, run or find games in the asia-pacific time zones. You can find it here: https://plus.google.com/u/0/communities/100566740249118526694
For other timezones, such as the American zones, a great place to start is here: https://plus.google.com/u/0/communities/107422815813208456454 It's an excellent community filled with friendly people.
Best Answer
Pre-generated characters save a lot of time, and remove the need to learn how to create a new character. Make sure everything they need to know is on the character sheet so they don't get distracted while reading the rulebook. D&D books are huge and complex. Another good point with that is that you can choose simple abilities that you know will be useful in your scenario.
Often when you play with the same group of people for a long time some habits of talking tend to replace official terms. When you are playing with beginners avoid the slang as it can be quickly very confusing.
Be helpful and forgiving: If a player move his character without noticing he would trigger an attack of opportunity when he could have avoided it, tell him that he can avoid this, show him how, and let him change his action if he wants to.
Considering rule simplification be careful you keep the game interesting enough for your experienced players. Maybe you can give the new player a free special ability which removes the need for magical components (or simplify an other part of the game). It could make you able to simplify even more the rules for the new players.