As you can see, figure environment is powerful in Authorea and you can do a fair bit of work with this environment. You may want to stick to uploading and adding caption to the figure unless you have conducted data analysis and want to share the data analysis as well. Now that we have covered how you can insert figures, let's move on to show you how you can insert citations in Authorea. 
 

How to work with citations and reference lists in Authorea

Authorea works using bibtex files. Bibtex are plain text files that store citation information \cite{fenn2006managing}.  If you are not familiar with bibtex, read the following document to get yourself familiar with the format, although you will not need to know much about bibtex format to work in Authorea but it is a good idea to browse this document 'fenn.pdf') to have an understanding:
Download the file to your computer and read it.