Good for you for taking the step to learn this stuff! It's actually a lot of fun once you get a grasp on the basics - I wish I had done it years ago (I'm 34 and just moved from managed accounts to DIY earlier this year.)
1. Go get John Bogle's book "The Little Book of Common Sense Investing." It's a quick read, and easy to understand (I read it in a day or two). It's full of facts and charts that show why it's actually more profitable in the long run to do yourself.
2. I would highly recommend moving your old account to Vanguard. The process is easy (you can start it online in like 15 mins). I used to have accounts with Fidelity, Franklin Templeton, and my husband with TIAA-CREF, and Vanguard is by far the best. They have an easy to use web interface, the app works great, they have extremely low fees, and a lot of educational stuff on the site. They are a not-for-profit company, and it's really ideal for learning. Customer service is great, too.
As for what type of account you will move your old retirement to, do you know what type your old account was? (401k, 403b, etc). There's two basic types of accounts - ones that took the money from your paycheck before taxes, and ones that take money after taxes. So you've got a couple options, depending on the type of account it is - here's some info from Vanguard about 401k rollovers:
https://investor.vanguard.com/401k-rollover/optionsThere's websites that help do the investment choices for you (like Betterment.com), but what I found is that I learned quickly, outgrew their service, and then had a bunch of money tied up in them. But if you really want to ease into it, look into something like that.