I wired a breaker box from a bldg. to my shop. It is a square d box I believe. When I turned the power on only breakers 2, 4, and 6 are hot. Each have 118 volts on them. Breakers 1, 3, and 5 have no voltage at all... why

You wired 240 volts from a double pole breaker? Only 1/2 of the supply is hot.

What kind of cable did you run (3-conductor with ground or 2 conductor with ground) and how did you connect?
Note: Ground and neutral must be separate in sub panel like this and ground rod must be installed.