How do you send a sim to work?

First they have to have a Job. From the job tab of the lower right menu chose a sim (that has the word "unemployed" beside it) and click on the word unemployed. If they already have a job ignore this part. Each job will have times - for example, a Fireman will go to work at 9 pm and stay there until 5 am. In that case, between eight and ten pm there would be a pulsing briefcase option beside that character in the Sims menu that shows all your sims. (Lower left.) click on it and that will send your sim to work. Remember not all Jobs start at that time, that was just one example. You can send your sims to work between one hour before their job starts and one hour after, so a two hour window. Hope this helps!