data0-data7 represents the 8 bits of the single byte being transmitted.
Code:
        data.bit0 = 1
        data.bit1 = 0
        data.bit2 = 1
        data.bit3 = 1
        data.bit4 = 0
        data.bit5 = 1
        data.bit6 = 0
        data.bit7 = 0
Copies means the number of times the transmission is repeated. You will need to experiment. If you always have a strong signal you might get by with a single copy; a weaker signal will require additional copies to set the receiver AGC and threshold. Most X-10 RF transmitters send 5 copies.

What I usually do on the receiving end is report the first valid code and then only report subsequent codes if they differ - with a time limit based on the time required to send the five (or whatever) copies.