Treshold calculation for linkage study

Hi everyone

I just recently done genomw wide SNP analysis on 20 N2 animals (SJL/ C3H cross) with over 300 polymorphic SNP`s. By using an affect only mapping strategy I plotted the number of mice which are heterozygotes against the loci of the mutation and found linkage on chromosome 8. Now the problem I have is that I have to calculate the threshold at p=0.05 for the number of animals. From a similar study I got given the following paper they have based their calculation on (see following link to access paper).

http://www.genetics.org/content/138/3/963.full.pdf

However since I have no mathematical background I`m completely lost by reading the paper and trying to figure out the math (Im already struggling to figure out what each symbol in the equation means). If anyone could help me that would greatly appreciated.

Thanks in advance

Alohaey