Websites of all types are available for starting a wiki, many are free. Here are a few websites that are useful for creating wikis: PBworks, wikispaces, and wikispot. Depending on the size and usage, upgrades are available that charge a small amount for housing information. Getting started is easy; first you just have to pick out a host website. Once you find a host website that works best for your Wiki you will need to come up with a name and URL.
Setting up the wiki is a step by step process, and there can be a bit of a learning curve for first time users, and for learning how to do specific tasks, like adding files and screenshots. All wikis are different so take the time to learn the different areas and then consider offering a training class to others in the office so that everyone understands and knows what their part is in contributing or editing information.
Once your wiki has the basics setup, you can either make it public or limit it to those you choose to grant access too. Everyone who is given access also has a setting given by the administrator as to whether they can only read the documents, or if they have editing capabilities. All of these permissions are granted by the administrator and can be changed at any time. At our library we grant administrative access to all librarians and staff so that they can add and change any documents necessary. Student assistants only have a certain section that they can access, and this section is available for them to be able to read and write in for logging activities and shelf reading assignments.
Overall, wikis are an easy tool to setup and utilize for everyday tasks and document handling. Below is a screenshot of my libraries homepage for the student assistant wiki.