SIESTA has a dedicated read-the-docs documentation site, with tutorials and how-tos. The main documentation page for SIESTA 5.4 (the only currently supported version of SIESTA) is https://docs.siesta-project.org/projects/siesta/.
SIESTA uses pseudopotentials, for more information please read the Pseudopotentials page.
Documentation for other libraries and applications of the SIESTA Project can be found at docs.siesta-project.org.
The SIESTA developers regularly run schools and tutorials. The contents of the SIESTA School 2023 are compatible with SIESTA 5.
A list of schools and tutorials can be found at the Events section. Older tutorials may be found at the Older Tutorials page.