Make sure you understand the problem - some can be analysed very deeply if you really grasp what's required, leading to a simpler solution.
If necessary, derive an equation, usually in the form x=f(y) where x is the desired answer and y is some arrangement of the available data.
Work out the limits for any search you will carry out: if you don't do this, your search may be impossibly wide.
Design an algorithm to solve the problem, using the equation if appropriate; a computer program must have a method for searching.
Write some code to implement it, using the equation and limits as above. Any language will do, with Basic being very popular in this field.
When you first try to run the program, frequently it either won't run or it won't behave as required. Debugging is the order of the day - this is often a large part of the task!
Check the result for accuracy and completeness. Make sure you've found all possible solutions.