Kitty,
You have selected the correct standard in ISO 9001.
Now scope your system development project and obtain to management approval for what you and your colleagues need to do.
And here is what you need to do:
Study the system that is the organization you work for, define its scope in terms of services, products and locations.
Work with top management to determine what the organization does to convert customer needs into cash in the bank, include interactions with customers and suppliers. This is your core process and it should fulfill the mission of your company.
Within the core process determine the key processes and the agree the names of the process owners with top management.
Then determine the processes that direct, enable and improve the core process (some of these may come direct from ISO 9001) and name the process owners.
Now you have a list of key processes each with a named process owner with whom you work to a capture the process as it is.
Deployment flowcharts are the tool I would recommend because they can be succinct describing who does what to fulfill the process objective and show the interactions of the entities and people who make the process effective.
Consequently, most of the documented parts of the management system are already implemented but you will have a few new processes (such as internal auditing) for which you will need to design the process and train the process team to make the process a reality.
For more background information search the Cove for developing a process-based management system.
Let us know how you do and ask away.
John