JeniMarie,
It depends where you live. In Michigan, you fill out an application at your local DHS office for assistance programs that include food, cash, Medicaid, and daycare. They will let you know which programs you are eligible for. (There is also a tool on their website on which you can fill in information and it will let you know which programs you are potentially eligible for). The application is online (to be printed out) as well as in the office, though you need to take it to the office when it is done. After it is filled out (correctly), a caseworker will be assigned to you and help you with the process. You can also fill out an online application for some medical insurance programs for pregnant women and children.
For WIC, find your local office and call them to set up an appointment. If you can’t get through on the phone, you may have to go there and make an appointment. Sometimes they will see you on the same day. Income limits are higher for the WIC program than most other programs.
Your state should have a website where this information can be found. Hope this helps!