what are the steps to take in programming an ic

First, go to ASCII data encoding information at Wikipedia.

Second, look up EEPROM at Wikipedia. (There are several options available these days for storing data, which are listed.) It is in this IC that an ASCII-encoded message may be stored for later retrieval.

Third, a counter IC may be used to step through the data which would be presented to a decoder IC (or more complex electronic circuit) to be presented to the display.

There is a lot involved in doing this from elementary electronic IC's, which is too involved to be explained fully in this forum.

A personal computer has the capability to do all the necessary functions, but cannot drive an LED sign directly. Electronics in the sign need to distribute information to buffers used to drive LED's.