[Xastir] Error msg

[Ben Bunch]

I have tried several times to get Xastir to completely install and when
I issue the ./configure command, it comes back with a: Configure Error:
no X11! Install xwindows development headers/libraries.

Can someone advise me on how to correct this? I have spent approx 15
hours attempting to download and install all the files listed in the
windows instructions and am getting frustrated. HELP!