Trying to figure out how to auto-start in my downstream jobs in my build chain to auto-start when previous build project completes

 I'm trying to figure out how to auto-start in my downstream jobs in my build chain to auto-start when previous build project completes.

E.g. 2 Steps in my build chain when step 1 completes successful build in a separate build project, step 2 in another build project (deploy) is notified to start deployment.