bMost of the information you need is in this Finesse Developer Center and there is a detailed presentation for Finesse Developers here https://communities.cisco.com/docs/DOC-28452
You can explore the Finesse Developer Center http://developer.cisco.com/web/finesse
and if you can’t find what you need, let us know.
For an overview of Finesse and creating Finesse gadgets http://developer.cisco.com/web/finesse/technical-overview
You will need a Finesse and UCCE lab. Getting started with that is defined here http://developer.cisco.com/web/finesse/getting-started-guide
Unzip the file and you will see a Gadget and Non-Gadget sample directories.
Copy the files from Finesse_9.1.1\samples\GadgetSamples to your 3rd party web server where you will be hosting your custom gadgets. (You can have the Finesse server host your gadgets by following the directions in Chapter 10 of the Finesse Developer Guide)
Then you will need to add the sample gadget to your Finesse Layout XML. For information on modifying the default layout see the Finesse Developer ppt here https://communities.cisco.com/docs/DOC-28452 and the Finesse Administration Guide
For the finesse gadget sample you will be adding something like
There is a presentation on creating a Finesse gadget here https://communities.cisco.com/docs/DOC-28452
Next try downloading and installing the other sample gadgets in the Sample Gadgets directory. You might start with Screenpop.zip
You can see a video on how to modify the screenpop gadget to screenpop your own url here: http://developer.cisco.com/web/finesse/videos
That should get you started. If you have any questions you can post them here or in a new forum thread.