My first question is do you know what a URL is in the first place? If so, then insert the tracker, where you are told to insert it. The explanation given is pretty straight forward on it's own. One might be confused, if they have never had or used an affiliate link or done any sort of marketing online.
If you are new to the aspect of marketing online and do not know the first thing about URLs, then it should be known this, in order to give you a better answer. However, the problem here seems to be that HubPages does not allow the use of URLs in this post, so it might sound strange, because it has to be explained in length, without the showing of a URL.
Thus, in the beginning of your the URL - "H" "T" "T" "P" with two forward slashes and then says "hubpages(dot)com", hub(if it's a hub), tag(if RSS feed), then INSERT TRACKER with a forward slash, then put the rest of the URL in place.
I think that is the best way I can explain it. Hope it helps.