With the following MWE you can use \footcite. Note that you have to use biblatex and biber to compile the MWE!
If you can't use biber change the biblatex option backend=biber to backend=bibtex.
MWE (name it for example mwe.tex):
\RequirePackage{filecontents}
\begin{filecontents*}{\jobname.bib}
@Book{Goossens,
author = {Goossens, Michel and Mittelbach, Frank and
Samarin, Alexander},
title = {The LaTeX Companion},
edition = {1},
publisher = {Addison-Wesley},
location = {Reading, Mass.},
year = {1994},
}
@Book{adams,
title = {The Restaurant at the End of the Universe},
author = {Douglas Adams},
series = {The Hitchhiker's Guide to the Galaxy},
publisher = {Pan Macmillan},
year = {1980},
}
article{einstein,
author = {Albert Einstein},
title = {{Zur Elektrodynamik bewegter K{\"o}rper}. ({German})
[{On} the electrodynamics of moving bodies]},
journal = {Annalen der Physik},
volume = {322},
number = {10},
pages = {891--921},
year = {1905},
DOI = {http://dx.doi.org/10.1002/andp.19053221004},
}
@misc{mozart:KV183,
author = {Mozart, Wolfgang Amadeus},
title = {Sinfonie g-Moll},
year = {1773},
address = {Salzburg},
note = {New K{\"o}chelverzeichnis Nr. 183, old version Nr. 25;
Erster Satz: Allegro con brio, Zweiter Satz: Andante,
Dritter Satz: Menuetto, Vierter Satz: Allegro},
}
\end{filecontents*}
\documentclass{article}
\usepackage[%
backend=biber, % <=============== possible: bibtex, bibtex8, biber
style=authortitle,
citestyle=authoryear-ibid,
sorting=nyt,
isbn=false,
doi=false
]{biblatex}
\addbibresource{\jobname.bib}
\begin{document}
This is text with \cite{Goossens} and \autocite{adams}.
And \footcite{mozart:KV183}.
\nocite{*} % <===== shows all uncited bib entrys in bibliography
\printbibliography
\end{document}
and the result:

Mozart is cited with \footcite. Also note, that your given code sbippets are based on BiBTeX, not Biber and biblatex.
Compile it with pdflatex mwe.tex, then biber mwe, then two times pdflatex mwe.tex. To avoid problems with your editor (which one do you use?) compile with this commands on the terminal/console.
If you use BiBTeX as backend change the compiling to: pdflatex mwe.tex, then bibtex mwe, then two times pdflatex mwe.tex.
Please have a look on the following question ShareLaTeX and biblatex with Biber