A: One bite at a time!



Like eating a whale, to send a string you just need to do it one byte at a time!

So the process is something like this:

1. Form the string to be sent;

2. Send the first byte (character);

3. Wait for that transmission to complete;

4a. If there's more characters to send, repeat from (2) with the next character;
4b If not, then you're done!

In an 8051, you identify when the transmission is complete using the TI flag - either by polling it, or by using the interrupt that it can generate.

Similarly for receiving.

Look at the FAQs - there's a whole section on Serial Comms...!