To add some structure to what others have said:
1) Pay off all debt except mortgage, pay regular payments on mortgage
2) Have 6 months of expenses saved in the bank for an emergency fund
3) Shoot for 15% of your gross income to allocate toward retirement investments...for you $11,250 or $937.50 per month
4) If your company matches a 401k contribution, contribute up to the amount they match. If that doesn't cover $937.50 per month, allocate the remainder to a ROTH IRA account. Like others have said, invest in a low cost target date fund or index fund. If you don't have a ROTH IRA, you can easily open one through Fidelity, Schwab, or many of the other brokerage firms out there.
5) After steps 1-4 are done, make sure you are investing for your child's college. You can contribute up to $2,000/year in an ESA. $166/month is easily done in most budgets.
6) If you find yourself with extra money at the end of the month after steps 1-5 and you want to save additional money for long term savings, I like using a robo investor like Wealthfront and have heard good things about Betterment. WIth Wealthfront your money is managed for free up to $15k (with a promo code...easy to find with a google search) then a .25% fee after that. You deposit the money and they take care of the rest. I like it because it has charts and graphs that make me not want to pull that money back out and spend it on something I don't need.
What is your interest rate on that mortgage? Even with a small balance, you may look into a refi if you have a higher rate than 4%...put that payment on a 10 year or 15 year and that will also accelerate your long term savings goals (provided that the new payment works in your budget).
Congrats on making some good progress!