You can find the most recent BOLTS for FreeCAD release at the Downloads Page.
There are different archive types available, if you are unsure, which to choose use the zip.
You can look up the location of the macro folder in the preferences: Choose
Edit->Preferences, in the dialog select the macro tab. The macro path is listed
there. On linux the macro folder is usually located at ~/.FreeCAD.
When you are done the macro folder should contain a subfolder called BOLTS and a file called start_bolts.FCMacro
The installation is now complete.
Start FreeCAD and choose Macros from the Macro menu.
In the dialog that pops up select start_bolts.FCMacro and click on
execute.
If you get an error that says something like:
No module named yaml
then this is because the yaml library for python is not installed. If you are using Linux, then you can usually get it using your package manager. If you are on windows you can get an installer here; you have to install YAML for the version of Python (first two digits) that is bundled with FreeCAD. You can find out which version that is from the first line of the python console in FreeCAD. If it is not opened, you can make it visible by checking it in the Menu View under point Views.
If you get an error that says something like:
No module named importlib
then you are using a older version of python where the importlib library is not included. You can get it here. For importlib no convenient installer is available for windows. Instructions on how to install a python module without an installer can be found here. Again you should use the version for the python version bundled with FreeCAD.
If you get a message that says
uic import failed. Make sure that the pyside tools are installed
or an error message that says
ImportError: No module named pysideuic
then there is a part of the PySide Qt bindings missing. For Debian and Ubuntu this is contained in the package pyside-tools.
On Windows it is sometimes necessary to copy the python dependencies to
<path to FreeCAD installation>\bin\Lib\site-packages
so that they are picked up by the python version shipped with FreeCAD. See also this thread in the FreeCAD forums.
If you get different errors, than please try the latest development snapshot. If it still does not work, please report that problem, and help me figure it out. The simplest way to do so is to use the comments below, but there is a number of of other places where you can report problems, a list can be found on the contribute page.
If you want, you can set up a toolbar button, or you can read how to use BOLTS for FreeCAD.