|The manual for the router should contain instructions on setting up wireless security. The type of security protocol you employ also depends on compatibility with the wireless cards in your various client devices.|
Regarding attaching your printer for network access, again it depends on the capability of the printer. You have not advised what make/model so we would be guessing. If the printer has an inbuilt network printserver, then it's operators manual will tell you how to get started. If it isn't a true "network" printer then it might need to be attached to a host PC or you may get a separate compatible printserver device.
Goin' Fishin' (Some day)