An External links section, if any, should always be placed at the end of the article. It should always be spelled that way, never "External Links" or "external links". The term should be used even if there is only one external link.
This page is written in British English, which has its own spelling conventions (colour, travelled, centre, defence, artefact, analyse) and some terms that are used in it may be different or absent from other varieties of English. According to the relevant style guide, this should not be changed without broad consensus.