You will need to do the following steps for QtCreator:
1) Go to Settings > Build and Run > Kits
.
2) Check if the auto-detection is correct. It is probably not if you have issues, so you will need to either set up manually or rreinstall QtCreator to see if the problem goes away. If it is not detected, you will have a read exclamation mark.
3) Add a new Kit.
4) Type a name.
5) You need to choose the proper "Qt version".
6) You need to choose the compiler.
7) Select the "Make Default" option.
As for command line, you should be able to do something like this to build a simple dummy main.cpp:
main.cpp
int main() {}
and then you can run the following commands in the (msys/cygwin/etc) prompt:
qmake -project && qmake && make