Building From Packages
This applies to the officially released packages.
Unpack the Mono runtime distribution:
tar -xjvf mono-X.XX.tar.bz2; cd mono-X.XX
Then configure, compile and install:
./configure --prefix=/usr/local; make; make install
This will give you a runtime, C# compiler and runtime libraries, where /usr/local is the prefix where Mono will be installed. You can change this to suit your needs.
If you are not using GNU/Linux system (such as Solaris or BSD variants), make sure to use GNU make.