Hi PopsicleJolt,
Welcome to the forum!
Here are the steps to create a Sim --- one you would like to play or not. If you don't want to play the Sim you've created, then, just place them in a house (explained in step 7).
1. Load you game
2. Select the world you want (Willow Creek, for example)
3. Click the "create new household to move in" icon of a person at the bottom right of the map view screen (the screen where you see all the lots in a world).
4. Clicking on the person icon will bring you into Create-A-Sim (CAS, for short)
5. Create a household.
6. Click the play button at the bottom right when you're done creating the household. Then, you will see a picture of the Sim or Sims whom you just created. Click save and play at the bottom right.
7. Click on an empty lot or a lot that you Sim can afford and you want to bulldoze and build a house yourself for your Sims. Click the confirm button at the bottom right.
8. Repeat steps 1 to 7 to add additional households.
After a few times, you will whip through these steps
. Happy Simming.
I hope this helps,
Coolsim