First, install pppd (the Point-to-Point Protocol package) and make
sure it is working.  You will need MS-CHAP support in pppd to use
encrypted authentication for pptp. 

Look at the Makefile; make sure its settings are correct.  In
particular, if your pppd program in not installed in either /bin or
/usr/bin, edit the path in PPPD_BINARY to point to your pppd program.

Type 'make'.  This should generate the 'pptp' executable.