How to exchanging code for an access token[facebook]

How to exchanging code for an access token[facebook]

I have problem with exchanging code for access token I try like this:
https://graph.facebook.com/oauth/access_token?%20client_id={387747397993215}%20&redirect_uri={http://mysite.com}%20&client_secret={AQAPBlfsNZihs0Ve43IbaykccXNnGkqXYg0PnwaXQUfjxaU5_DezT9LZqoQ2ma6mO5miaOKAa7Cf0YPQRnco8f4k8rfxJOENaNiD8rtK152PXdtBYN86arwv5UCan3tCX4kG_UWDreRkeT6S_X2MsWLFs-}
I get this error:
{
"error": {
"message": "redirect_uri isn't an absolute URI. Check RFC 3986.",
"type": "OAuthException",
"code": 191
}
}