No, Varsha, right now, you won't see any submission link, the submit button is invisible but exactly at 6 PM (when this particular Happy hour starts), you will see the SUBMIT button right below the time ticker (and to the right of the "Vouchers left" tab.
Since there are only 50 vouchers in total, so you will have to be fast in submitting or else you will miss the bus. Therefore I will suggest you to be online from 5:55 pm onwards and keep the happy hours page open.
As soon as you see the submit button, click it. You will be taken to a new page where you will be asked to enter the url of your blogpost, the title of the post, a short description of it and tags. Enter them quickly and press the submit button. If your post is successfully submitted, you will get a message saying "your post will show up on your Indivine list once it gets moderated".
Now to know the rank of your submission (at what position did you submit your post), at once head to indistatus page - first to the dashboard page and then on the right side column, you will see Indistatus tab.
Once you are on the Indistatus page, scroll down to the particular Happy Hours tab. In the "Entries" column, right now we see two zeroes for "Total" and "Mine" (since the submissions haven't started yet). Once you have submitted your entry at 6 pm, you will see "1" written under "Mine" and a certain number under "Total" (i.e. the total number of entries at that point). That number will be your submission rank (it may not be exact because many other bloggers too would be submitting their entires simultaneously, but it will give you an approximate rank. If you succeed in submitting your entry within 50, you will win a voucher, provided your post meets all the criteria. Good luck 