It seems to me that you should start off with some basic reading on the 8052.

Obiously, there is a big difference between input and output. To control an output, you write to it, and to determine the state of an input, you read it. Writing to an input, as you suggest, is useless.

As for the "commands" for I/O operations: as indicated in the 8052 documentation provided on this site, you can use all instructions that allow you to read from and write to the special function registers.