Complex sentence: Fraser did not finish high school, or have any formal training-but after being conscripted in the then South African Defence Force, for a 2 year period 1981-1982-he began to write and perform his own material from 1985 onwards.
Split into simpler sentences: Fraser did not finish high school, or have any formal training. After being conscripted in the then South African Defence Force, for a 2-year period (1981-1982), he began to write and perform his own material from 1985 onwards.