|Make and model number of camera could help to identify connection problems with usb.|
As a general rule popular makes will be automaticly detected when plugged in, some may need drivers from the maker.
For instance my Canon gets loaded automaticly for file transfer.
If your camera has a problem being recognised as a usb device, a card reader can solve that.
SD cards are usually stored in the same compartment as your batteries and may need to be pushed down first before they are free for removal.
If you have a medium priced recent printer/scanner, chances are it has a card reader built in, or there may even be one fitted on the front panel of your computer.