You need to compile the bibtex file.
Suppose you have article.tex and article.bib. You need to run:
latex article.tex(this will generate a document with question marks in place of unknown references)bibtex article(this will parse all the .bib files that were included in the article and generate metainformation regarding references)latex article.tex(this will generate document with all the references in the correct places)latex article.tex(just in case if adding references broke page numbering somewhere)