The classes are organized in a number of different ways, weekends, after work, etc. You should be able to find a course that meets your schedule.
Most dive shops provide dive instruction.
They can be found in your local telephone directory. You should find a friend to take the course with, that way you'll also have a dive buddy. After your pool and classroom work, you'll be given a written test, not too difficult. The final step to getting certified is your required certification dives. These are fun.