Application letter for travel approval

I want to draft a cover letter convincing the embassy about the reason for my travel. I have to attend a training workshop which is really important for my HR Career and progression as well. This workshop will be held in Chicago and I will be travelling from India. Reason along with details in application letter needs to come out very strongly that I am travelling and I can not miss this workshop at all, as it is business critical. How will it help me in my HR career? Why it can not be missed? Why is it so important for me to attend? Please help in detailing out all these things in my letter. Request your help in revising the day wise agenda content in attached word document.. Please make it really effective and business critical document. I am also attaching the day wise agenda of the 3-day program. Please refer to the same to work on my application letter. I need this by today positively please. I am working in Consulting industry, and this workshop will also include topics relevant to consulting related work. Please touch base on these aspects as well that this will be relevant to my industry as well.