Some writers find the first page especially daunting. It seems to carry the weight of all the pages to come. In fact, it's just one page.
Three hundred words, on average.
Yes, it's true that eventually, when you are doing your subsequent drafts, you will want to be sure that the first page grabs the reader (you'll find a tip for here later) but for now just do the best you can and move on.
One writer I know skips the first page in order to avoid this pressure. He just jots down something like, "Jack sits on cliff, contemplating whether to jump. Decides to call his ex-wife." Then he writes the phone call with the wife and the rest of the first chapter. When he has finished his first draft he goes back and writes the first page.
Quite often what you believe will be the first page ends up not being the first page at all. You may decide when doing the second draft that you should have started the story later or earlier. Or you may come up with a better setting, or decide to add or subtract a character, or make some other change that requires a new first page.
Don't let the idea of the first page put you off--cut it down to size, mentally, and get writing!
(Want writing advice from the very best? Writers like Mark Twain, Jane Austen, Charles Dickens as well as modern masters like Kurt Vonnegut, Ray Bradbury and Martin Amis? You'll find it in "Your Creative Writing Masterclass," published by Nicholas Brealey and available from Amazon or your other favorite book seller.)