First you must pay the card’s M€ cost. Then the lower panel of the card shows you any immediate effects. These effects (and other effects triggered by the card you just played) are performed in any order you choose.
Any production must be performed. Resources or production with a red frame means that you can affect any player you choose (even yourself). Resources or production without red frames always affect yourself and must be performed.
Cards may also feature tiles and tags with a red border, and that red border signifies that you may target any player’s tiles or tags. This is also specified in the card text.
Any resources are gained, or removed. Again, a red border means you can choose the resources of any one player, so playing red cards is usually not very nice to other players. Red-bordered resources are optional, though, so the card does not force you to remove your own resources, even if you are the only player that has any of the resource in question.
Non-standard resources (that are not collected on your player board) are instead collected on specific cards. By default, those resources are usually placed on the same card that generates them.
Any tiles placed by a card follow the rules for tiles. If a card symbol has an asterisk (*), then it is an exception to the normal rules, and you must read the explanation in parenthesis to see details of how the card works.
VP icons serve no function during play, but will be counted in the final scoring.