If you have SWP, view directly the *.tex file. Otherwise, save to disk the *.txt file as a plain text file, and either read it as such, or use your favorite LaTex compiler on it, after commenting out (if I have not done it for you) lines that are peculiar to SWP, such as
\input tcilatex
There may also be SWP macros to be touched up. For instance, change \dfrac to plain \frac