If you want to use your own SAP system landcape you have two possibilities to install & use SAP Netweaver Gateway.
First, you can install your SAP NetWeaver Gateway as a standalone platform and, it that case, you can connect your Gateway Platform to any of your SAP ABAP Back End platform (ECC, CRM, SRM, and so on...). But if you want to use the "screen scrapping" or "eventing" functionalities from your SAP ABAP Back End, your Back End needs the SAP_BASIS 7.0 SP18 installed on it to then install the IW_SCS (SAP Netweaver Gateway Screen Scrapping to create service directly from a screen selection) and IW_BEP (SAP Netweaver Gateway Backend Event Publisher to publish objects event & workflows event) components on it. If it's not your case you could only use "Remoting call" functionality based ont the SAP RFC technology which is available from more than 10 years on any SAP ABAP platform As a reminder all the demos on the Adobe labs are based on RFC consumptions.
Second, you can install all your SAP Netweaver compoent on your existing SAP Back End system but, for this, your SAP_BASIS has to be in version 7.02 (SAP netWeaver EHP 2) in SP 7 (Support Package 7) has mentionned oin the SAP online help: http://help.sap.com/saphelp_gateway20sp02/helpdata/en/d1/45a4aafd6344728dbe2c3bf19beb9e/fr ameset.htm
You can check your compent version of SAP_BASIS installed on your Back End from any SAP GUI transaction. click on the "System" menu entry & then from the "status" sub menu. then click on the component details button from the popup window.