The guides are a good start: spring.io/guides
Baeldung also has good guides: baeldung.com
The documentation per project is also good, if you need to go into a lot of detail.
If you want to get started quickly with spring I would suggest Spring Boot: projects.spring.io/spring-boot It provides an opinionated, configured starting point for most projects.
Also start.spring.io as a place to generate Spring projects with all the dependencies you may need.