1) Please refer WSInstallAdminGuide to install GP web services on GP 2010 /2013

2) Once web services are installed, please refer the "Gorilla Expense Great Plains 2010 Setup.Docx". This document can be used for GP 2010 as well as GP 2013. 

This document is an important web service configuration document that covers the following points -

a) Provide access to AP users to use web services to post data to GP

b) Update default web service policies / rules 

PS - If you are sending data from Gorilla Expense to GP Project Accounting or GP with MEM, please install eConnect instead of GP Web Service. eConnect needs to be installed on the GP server and on client machine where Gorilla Expense Integration App will be installed (typically AP Managers machine)