To do this you would type:
command1 && command2
command2 will be executed if command1 successfully completes (if command1 fails command2 won't be run). This is called a logical AND.
command1 || command2
command2 will be executed if command1 does not successfully complete (if command1 is successful command2 won't be run). This is called a logical OR.
To execute commands sequentially regardless of the success/failure of the previous you simply type:
command2 will execute once command1 has completed.
More than two commands: You can continue to use ';' (semicolon) characters to do more and more commands on the one line.