Motor Control/ Optical Encoder and Solenoid

[kohokoho]

I am planning to use an optical encoder to sense the position of the rotating dome of an observatory in an attempt to automate the dome rotation using remote computers. (The dome rotates using NEMA 56 C face motor). I have picked the encoder, but don't have any clue as to how to interface the digital signal coming out from the encoder to the computer. I am very new to the concept that is needed here.

 

Secondly, I am thinking of using a high force pull style linear solenoid to unlatch the lower shutter door from the upper door to view different angles in the sky. Would a relay/switch work for the solenoid? I know the solenoid is activated by power, but what do i need to use to activate it from a computer? Again, I am very new to controls.

 

I'd appreciate anyone's help in this.