The toolkit uses jQuery. It has been tested on jQuery 1.4.4, but other versions may also work.
You must add the correct REST endpoint hostname for your instance (i.e. https://na1.salesforce.com/ or similar) as a remote site in Your Name > Administration Setup > Security Controls > Remote Site Settings.
Using the Toolkit
Create a zip file containing forcetk.js, jquery.js, and any other static resources your project may need. Upload the zip via Your Name > App Setup > Develop > Static Resources.
Your Visualforce page will need to include jQuery and the toolkit, then create a client object, passing a session ID to the constructor. An absolutely minimal sample is:
A much more fully featured sample is provided in