You can try to "auto-manually" add your GPUs to bfgminer by pressing
+ and then typing
auto, or you can use the
-S opencl:auto option when launching bfgminer.
NOTE: Not all graphics cards are compatible; various software is required (e.g., AMD APP sdk); it is not recommended to use GPUs for bitcoin mining with bfgminer.
According to README.GPU, the official documentation for bfgminer on github:
By default, BFGMiner will NOT mine on any GPUs unless in scrypt mode. If you
wish to use your GPU to mine SHA256d (generally not a good idea), you can
explicitly enable it with the -S opencl:auto option.
To start scrypt mining with bfgminer and GPUs, use the
-S opencl:auto options, but keep in mind that there are several other parameters to consider. See README.scrypt for additional details about scrypt mining configuration and optimization with GPUs.