There are a number of options when it comes to using software to help create a logic model. These range from generic word processing tools (Word, Powerpoint, or their Google Doc or Mac equivilants), to software that has been specifically tailored for visualising Theories of Change, like TOCO or Miradi. You should consider what resources you have to invest in software, both in terms of cost and in time to learn and use the features. If you only have a short timeframe and have simple needs, then a basic tool may suit you better than some of the more complex software available. It's important to investigate a few options and see what is going to be best for you.
Workshop: Using program theory and program logic for improved evaluation practice (Sydney 1 June 2016)
This 11-step guide defines program evaluation, what it is used for, the different types and when they should be used. Also covered is how to plan a program evaluation, monitor performance, communicate findings, deliver bad news, and put improvements into practice.