First Download STS(Click here)
Here We download and install spring tool suits step by step for windows operating system . if you download for another operating system select option accordingly
When you click this link.it downloads the jar file. after download double click on the jar file. It's automatically extras.
in this image you can see the spring-tool-suite-4-4.6.1.RELEASE-e4.15.0-win32.win32.x86_64.self-extracting.jar file
After double click spring-tool-suite-4-4.6.1.RELEASE-e4.15.0-win32.win32.x86_64.self-extracting.jar file automatically extract
After extract spring-tool-suite-4-4.6.1.RELEASE-e4.15.0-win32.win32.x86_64.self-extracting.jar file directory structure.Now click the eclipsec.exe now open spring-tool-suite IDE