The 'build' command is only supported from within a workspace-SOLVED

I install tensorflow by python-pip. it works but when i run my project,  the IDE warns me that :"The TensorFlow library wasn't compiled to use SSE4.1 instructions, but these are available on your machine and could speed up CPU computations"

I serach the on the overstack and get the answer here. i need to build tensorflow from source like this command:

bazel build -c opt --copt=-mavx --copt=-mavx2 --copt=-mfma --copt=-mfpmath=both --copt=-msse4.2 --config=cuda -k //tensorflow/tools/pip_package:build_pip_package

But new error arises :"The 'build' command is only supported from within a workspace"

Solution:

mkdir tensorflowcd tensorflowtouch WORKSPACE