PostRFP's vendor evaluation tools are easy to learn and can be used immediately. Using PostRFP is similar to using other popular web sites - it's fairly intuitive. If you understand the principles behind RFP style vendor evaluation, and you are familiar with the web, you should be able to get started without training.
For documentation, two detailed Guides are available as PDF or HTML documents from the Help link within PostRFP:
Some of PostRFP's vendor evaluation tools are a little more subtle. One is designing multiple column questions, for which a basic understanding of table design (row-span and column-span) will be useful. Another is the use of different approaches to calculating total weighted scores, which can become confusing in a big RFP questionnaire with deeply nested sections.