I have not worked through the tutorial personally and I don't have time to do it right now. Unfortunately that error is not specific enough for me to help you to much.
I do suggest you download his finished project from his github site and import it into STS as a maven project, and see if you get the same errors. If you don't you can start comparing what you did differently or what you might have missed.
Probably not. Everyone uses Maven or Gradle to build their projects, with Maven being the more prominent of the two. If you are not familiar with it you should be getting familiar with it. Building Spring 3.x projects without it is just painful. It really is as simple as downloading STS and importing a maven project and pointing at the directory containing the pom file.
subject: jgrid - Spring MVC CRUD operation with pagination and without page refresh