The QtCreator doesn't support cmake-projects very well as far as I know. You can add a new file with "file -> new ..." or by pressing ctrl+n, then specify the path and add it manually to your CMakeLists.txt. After that you can run cmake from the menu. That's the way I do it at the moment.

The only evidence for this bad support I have found is this forum post. It seems that nothing has changed since then.

If you want to change your IDE, maybe have a look at KDevelop as it seems to have a better cmake support (I haven't tested it yet)

//Before Edit:

source: http://wiki.ros.org/IDEs

QtCreator

As QtCreator supports opening CMake projects out of the box ,it does not require a setup procedure if started from a terminal. Note that this is absolutely crucial, because otherwise the environment will not be set correctly and functionality related to rosbuild or catkin will fail when running cmake.

Note that instead of starting QtCreator from a terminal, you can use the following desktop file and use it in your launcher:

$ cat qtcreator.desktop 
[Desktop Entry]
Exec=bash -i -c qtcreator %F
Icon=qtcreator
Type=Application
Terminal=false
Name=Qt Creator
GenericName=Integrated Development Environment
MimeType=text/x-c++src;text/x-c++hdr;text/x-xsrc;application/x-designer;application/vnd.nokia.qt.qmakeprofile;application/vnd.nokia.xml.qt.resource;
Categories=Qt;Development;IDE;
InitialPreference=9

In Ubuntu 13.04 and later, the third line must read:

Icon=QtProject-qtcreator

This is the standard QtCreator desktop file, except for the Exec line that has been modified with "bash -i -c". More about desktop files and their locations for Ubuntu can be found here. Note also that the same trick can be used with eclipse.

If you are experiencing issues with the qtcreator package shipped by Ubuntu when opening the CMakeLists, then try installing QtCreator from Nokia's installer.

rosbuild

To open a rosbuild ROS package code as a project, use "Open File or Project" and select the CMakeLists.txt of your ROS package. Take care to select the "[package_name]/build" directory as the build directory, which is the ROS default. On the next screen click 'Run Cmake' and then Finish. This may not show all the folders such as launch and include in the project tree. If you want to choose the files manually, goto File->New File or Project->Import Project->Import Existing Project and selected to choose all files/folders included in the project.

catkin_make

To open a catkin code as a project, use "Open File or Project" and select the top level CMakeLists.txt of the catkin workspace (e.g. "src/CMakeLists.txt"). Select the catkin build folder as the build directory and 'Run CMake' (in order to enable debugging add following line into arguments edit box: -DCMAKE_BUILD_TYPE=Debug).

Recently this has started to fail, because the main CMakeLists is a symlink to a non writtable location. The workaround is to make a copy ... (more)