coolrunner II and DIo4 interconnect

I'm currently using coolrunner ii Xc2c256cxl as my system board and DI04 as my I/O board. Using verilog, i am having problem turning on the 7-sement display. any link or verilog code that help me understand how to implement this is well appreciated. attached is my verilog code. the problem is the 4 common anode lines, how to turn it on inside my code.

module seg_disp(input b1, b2, b3, b4, output SA,SB,SC,SD,SE,SF,SG);

wire [3:0] HEX = {b4, b3, b2, b1} ;
reg [6:0] led;
assign { SG, SF, SE, SD, SC, SB, SA} = led;

always @(HEX)
case (HEX)
4'b0001 : led = 7'b1111001; // 1
4'b0010 : led = 7'b0100100; // 2
4'b0011 : led = 7'b0110000; // 3
4'b0100 : led = 7'b0011001; // 4
4'b0101 : led = 7'b0010010; // 5
4'b0110 : led = 7'b0000010; // 6
4'b0111 : led = 7'b1111000; // 7
4'b1000 : led = 7'b0000000; // 8
4'b1001 : led = 7'b0010000; // 9
4'b1010 : led = 7'b0001000; // A
4'b1011 : led = 7'b0000011; // b
4'b1100 : led = 7'b1000110; // C
4'b1101 : led = 7'b0100001; // d
4'b1110 : led = 7'b0000110; // E
4'b1111 : led = 7'b0001110; // F
default : led = 7'b1000000; // 0
endcase



endmodule