how to connect analog input directly to FPGA Altera board?

hi;

I want to implement Sigma Delta ADC on Altera DE1, i wrote the code and run on QuartusII; now i want to know

is it possible to connect the analog input directly to the board?

as in my code the input is introduced as signed [7:0] so my original analog input should be converted to the type signed [7:0] before enter the altera cycloneII core is this conversion possible on the board?

at the end how can i get my digital output from the board and analyze it?

your guidance is very appreciated.

thank you