Here is a list of useful Fate/Grand Order links that will be helpful to you. Be sure to check them out.

Fate/Grand Order Official Website
Official website in JP.

Fate/Grand Order Official English Website
Official US Release website.

Fate/Grand Order Cirnopedia
Basic Guides, Servant and Craft Essence Database, and Quest listings. This should be the first site you check for how-to-play questions as it’s most likely that they have already covered it.

F/GO Kazemai
Website that hosts data-mined information from the game. It is in Chinese.