Really mate it just boils down to how willing are you to do it, how well do you understand sql servers in general, how well do you understand SQLSRV api (as the MSSQL api has long since been dropped)
You will have to create a database table that associates vote information against accounts, you will then need to create an html form lets call him "vote.html" where a user will visit and based on some php coding buttons will be available with timers/not etc..etc.. (most people code their voting systems to match vote site timers -- usually 12 hr)
This page will allow them to click a button which will redirect the user to the voting site (to my knowledge there is only a couple vote sites which offer call backs which confirm the users successful vote) You can then use some mock rules or java to make it seem like the user is actually forced to vote (but unless you program an actual program you can not be sure at all -- unless using one of the afore mentioned vote sites)
You will also need a verification functions to make sure the user isn't sitting there pressing the button over and over again or using scripts out of order. It is a lot more work than just slapping one together (I know because I've personally wrote three different vote systems from the ground up)
I can offer you some tips and hints but my full services are not free, I will build you vote system for a price. You can see my specialties in my signature.