I can't speak to platforms for promotion of the offer. I can speak quickly to the layout of your entry form.
UI on the Entry
The "Quote" button got in the way of the "entry" with the comments. I would replace the "comment" field requirement (see below) and I would make a clear "Submit" button -- I would either have the "free quote" be a second step, or make it auotmatic as part of the confirmation. I found it confusing. I wanted to click
Replacement of the Comment
I don't think adding a comment adds much to the process, the user is doing it, and it is clunky. I would replace the comments with a real social media strategy. I would put the click through to the social media share as the second step of registering for the content. Step 1: Information, Step 2: Social Media Like on Facebook, Step 3: Submit confirmation and request for free quote. I would also have the three steps able to be seen without having to scroll down on the page.
Power of Social Media
Today's websites are all about integration with social media. I don't see how you are leveraging social media to promote the contest. Don't you want every person who applies to promote it through their friends/families/employees? Why not give the community the option to vote on which one makes the most compelling case? My assumption is that might have been what you were doing on the comments -- I don't think it worked. I would try something else.
I found it very difficult to find your portfolio and view it in a way that would allow me to assess whether your company's work is the type that I would consider for my own business. Perhaps having linked on the contest site a portfolio link that allows me to see and go to 3-5 other webistes your team has developed.
I searched "Free Website Contest" and found 30,000 hits -- of which every one on the first page was a contest announcement. Why would someone choose to enter yours rather than someone elses? Because the sites that you have done and your niche market overalp their sector and goals. Well, not really -- they will choose yours because sites you have done fire their imagination of what they could win.
Ask yourself how easy it is for a prospective contest entrant to see and view your profolio.
If the goal is to secure leads. My guess is that you are hoping to sell new website packages to prospective clients. I am curious if the profile of a company seeking to win a free website will be the same profile that will result in good business for your company.
For your companies development, the successful showcasing your companies skills and abilities in website development and promotion through this contest demonstrates the skills that a propective client will be purchasing. Building websites that will work-- also means building a content squeeze page the converts leads to prospective clients.