Hi Karthik
The BIT series of Workflow are copyright material of SAP and sharing openly like this is not a good idea. 
if you need them, contact SAP education, via your organization, to get this material.
SAP Education - India:
https://training.sap.com/in/en
SAP Workflow Associate training and certification:
If you need these to prepare for Workflow Certification and do not have the funds to invest on the full blown certification training program, just get your hands on the following "Best Book Ever':
This will be quite cheaper as compared to wf certification training....AND much comprehensive as it has been written by some great minds!
If you need to build your knowledge from basics and need some free stuff, check the following links:
An introduction to SAP Business Workflow
http://scn.sap.com/docs/DOC-31056
Building a Workflow From Scratch
http://scn.sap.com/docs/DOC-3224
A Beginner's Guide to Workflow and WebFlow
http://scn.sap.com/docs/DOC-3024
A little help for SAP Workflow 'freshers' (part 1)
http://scn.sap.com/community/bpm/business-workflow/blog/2011/02/15/a-little-help-for-sap-workflow-freshers-part-1#
Workflow Recipe for Passionate Starters - Part I (Spice up!!)
http://scn.sap.com/community/bpm/business-workflow/blog/2012/05/18/workflow-recipe-for-passionate-starters--part-i-spice-up
Workflow Recipe for Passionate Starters - Part II (Spice up!!)
http://scn.sap.com/community/bpm/business-workflow/blog/2012/05/18/workflow-recipe-for-passionate-starters--part-ii-spice-up
Workflow Tutorial:
http://****************/Tutorials/Workflow/Workflow.htm
SAP Business Workflow on SAP Help
http://help.sap.com/saphelp_46c/helpdata/en/c5/e4a930453d11d189430000e829fbbd/content.htm
Workflow transcations:
http://help.sap.com/erp2005_ehp_02/helpdata/en/9b/572614f6ca11d1952e0000e82dec10/frameset.htm
Using ABAP OO in Workflows:
http://scn.sap.com/community/bpm/business-workflow/blog/2006/07/25/using-abap-oo-methods-in-workflow-tasks
regards,
Modak