Welcome to the forum. You've come to the right place. Many of us arrived here knowing even less about investing than you now know. The posters above are right that you need to start with educating yourself about personal finance and investing. Some of the basic books recommended are a good start. That White Coat Investor guy isn't very smart and he's full of himself (and smells badly), but you just might learn something from his website.
A few tips to get you started.
1) Investing isn't something you do outside of your 401K. It's something you do inside and outside your 401K.
2) Sorry to hear about the divorce. Unfortunately for docs, we're much more likely to lose our money to our spouses than to our patients. Between child support and alimony, your disposable income will now be severely limited. You need to put about 20% of your income toward retirement, whether it is inside a 401K, in another retirement account, or in a regular old taxable account. If you cannot now do this, you probably need to pare back your lifestyle a bit. Either that or you'll be like the old bitter docs you see around the hospital still working all night at age 68.
3) You may or may not be able to get $200K per kid in time for college. That's okay. There was a recent article published saying they get better grades if they have some skin in the game. Community colleges and state schools are also a lot cheaper. The private university I attended still has tuition less than $5K/year. There are plenty of good educations available for less than $200K. Make sure you don't sacrifice your retirement for their education. One of the best gifts my parents gave me was to ensure they would be financially independent in their old age. They didn't give me squat for college though. That said, if you really want to have $200K each, let's take a look at what that means. Let's say you have a 3 year old and a 5 year old. So you want $200K in today's money in 13 years and $200K in today's money in 15 years. How much do you need to be putting into 529s each year if you can get a 5% real (after-inflation) return? About $11K/year for the older one and about $9K/year for the younger. I'd recommend you use a 529 for that. Check with your own state one and if you don't get any significant deduction use the Utah one. You may also want to look into the Private College 529, a pre-paid plan that can be used at any of 270 private colleges. I figure if you plan to spend $200K you probably want one of those schools anyway.
4) A 401K is a tax-protected account. The money grows tax-free. When you pull it out in retirement, you will pay taxes on every dollar at your regular tax rate. Your effective rate later will probably be better than your marginal rate now, so that's a good deal. But you don't pay taxes on it until then.
5) There's nothing wrong with real estate investing, but in many ways it can be like a second job. Many people here invest in REITs, which are a real estate investment that trades on the stock market. It's a lot less hassle and no one calls you to unclog the toilets, which really sucks after a long day at the hospital. By the way, since your parents have lots of funds, why not have them kick in some funds toward those 529s?
Good luck investing. Just by arriving here the battle is half over. Now go read a few books. This stuff is way easier than your neurology course as an MSII.http://whitecoatinvestor.com/books-4/
1) Invest you must 2) Time is your friend 3) Impulse is your enemy | 4) Basic arithmetic works 5) Stick to simplicity 6) Stay the course