Hi,
You will find general instructions for installing libraries (including the CAPA library) at
http://webwork.maa.org/wiki/Installation_Manual_for_2.4_on_Ubuntu_9.10#Install_the_WeBWorK_Problem_Libraries
Specific instructions for the CAPA library are at:
http://webwork.maa.org/wiki/CAPA_Physics_Problems
Note that for CAPA you also need install the macros and graphics and the above instructions include instructions on this.
Arnie
WeBWorK Problems
Installing a new library
This forum has a limit to the number of forum postings you can make in a given time period - this is currently set at 10 posting(s) in 1 day