How do I go about getting my 401k money back from my previous jobs?

When you say you want to get your 401(k) money "back," do you mean you want to roll it over to an IRA? This is really quite easy - decide where you want your rollover IRA to be (i.e. Fidelity, Vanguard, Schwab, etc), and then you can set up your rollover account on line, as long as you have an account statement from your old 401(k) plan. The IRA administrator will do all the paperwork to roll the money from your old 401(k) into your new account. Doing a direct rollowver like this avoids any tax consequences for you.

If, however, you mean you want to make a withdrawal, you will have to contact the administrator of the 401(k) directly. You should be able to find contact phone numbers either on one of your quarterly statements, or ask the HR department at your former employer. I'm sure you are aware that there may be significant tax consequences to taking a withdrawal if you are under 59-1/2 years of age.