Hi Carman;
The attached image is a basic 'line diagram' of an Infantry Battalion in 1944, thought this would make it easier for you to understand what Companies are. Basic breakdown is a:
Battalion Headquarters (BHQ)
and six Companies:
Headquarters Company ("HQ" Company)
Support Company ("SP" Company)
Rifle Company ("A" Company)
Rifle Company ("B" Company)
Rifle Company ("C" Company)
Rifle Company ("D" Company)
Hope this helps.
Cheers