textpad tech support

I have not used complex regular expressions before and I’ll I’ll be darned if I can figure out textpad’s regular expressions help file.  Here’s what I want to do.  I have a codebook with entries like this:

99999  Something County

and I want to use search and replace in textpad to turn all these lines into  this:

replace countyname=”Something County” if fips==99999

Anybody know how?