If this is a single linked list with a head pointer

How can I change the pointer to point to Tail?

Code:
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define MAXLINES 50
#define MAXWORDLENGTH 50

FILE *ifp;

struct word_link
{
	char word[MAXWORDLENGTH];
	struct word_link *pnext;
};

int main(void)
{
	const char ifn[]={"word.txt"};
	char line[1+MAXLINES];
	struct word_link *phead,*pthis,*pnew;
	
	ifp=fopen(ifn,"r");
	if (ifp==NULL)
	{
		perror(ifn);
		exit(1);
	}

	phead=NULL;

	for(;;)
	{
		fscanf(ifp,"%s", line);
		if (feof(ifp)) break;
		
		if ((pnew=(struct word_link *)malloc(sizeof(struct word_link)) )==NULL)		
		{
			fprintf(stderr,"link1: no storage available\n");
			exit(1);
		}
		
		strcpy(pnew->word,line);
				
		pnew->pnext=phead;
		phead=pnew;		
	}
	
	for(pthis=phead;pthis!=NULL;pthis=pthis->pnext)
		printf("%p  %s\n",pthis,pthis->word);
	
	free(pnew);
		
	fclose(ifp);
	
    return 0;
}