Each trading card should have a card page, which will include 3 images (the card, the foil version of the card, and the card's artwork), as well as information about the card, including the card's name, the game it's associated with, the card number, and more. In order to keep these pages uniform, a template has been created so you only have to fill in information.
The first step to creating a new trading card page is to copy the blank template from this page. Because it's Wikitext, the visual editor won't be able to handle it correctly. Instead you'll need to use 'source mode' in either of the two editors to make changes to it.
Once you've copied and pasted that blank template to the new page, all you need to do is fill in the blanks, after the equals sign on each line.
The different functions are:
CardImage = the file name of the image of the normal version of the card (please use the same image that's on the game page - no need to create two versions of the same image). Be sure to include the file extention (usually .png).
FoilCardImage = Similar to CardImage, except this is the file name for the foil version of the card.
CardArtwork = File name for the image of the card's artwork, if it's available. Like CardImage and FoilCardImage, this file should be same as is on the game's page. The file extention for card artwork is usually .jpg. If the card's artwork isn't available yet, just leave the line blank.
CardName = The name of the card.
GameName = The name of the game that the card is from. This should preferably be a link to the game's page.
Series = Theoretically, games can have more than one series of cards, though so far only series 1 has been seen.
CardNumber = The number of the card, out of the total number of cards in the series. This will generally be written as "X of Y". The order of the cards is determined by their arrangement on the badge page in Steam. If, for example, a game has 8 cards, the first one would have "1 of 8" for this line.
Description = Most, though not all, cards have some sort of description about the artwork or what's going on in the game. If you have the card in your inventory, selecting it in your Steam Inventory will display the description. Otherwise, it can be obtained by searching for the card in the Steam Marketplace. If there's no description, just leave this line blank.
Trading card pages should have the category "Trading Cards", "Series 1" (or 2, if a game ever gets a second set), and the game's name.