In Quartus you have two methods of design input. HDL (Hardware Description Language) or schematic entry. When you use schematic entry you usually have access to a library of modules. One of the modules in a library is likely to be a multiplexer of some description. I need to know what kind of multiplexers you have available. What's so hard about that?
I watched tutorial videos, write some hdl codes. But i don't run my code anywhere.
Debasedly Ex:
module part1(SW,LEDR);
input[9:0] SW;
output [9:0] LEDR;
assign LEDR=SW;
endmodule
It looks like you are trying to write VHDL. To see your code working you need a functional simulator, or you need to do the syntheses step and load the code into an actual device.