How to write an algorithm for a Turing machine?

Question

Algorithms

Can you help me solve the problem of writing a program for a Turing machine?
A={0,1,3} Let P be of the form Q–R, where Q and R are non-empty words of symbols 0, 1, and 2. Treating Q and R as numbers in ternary notation (possibly with non-significant zeros) and assuming that Q≥R, give as an answer the record of the difference of these numbers in the same ternary system.