need help with my c programing question.

Hi Guys i need help with this question . i already try to do many time but, i cant figure it out wat is the problem

this is the question

Write a complete C program to accomplish each of the following. Assume that all the manipulations occur in main (therefore, no addresses of pointer variables are needed), and assume the following definitions:

		struct gradeNode 
 		{ 	
	char lastName[20];
	float grade;
	struct gradeNode *nextPtr;	
		}

		typedef struct gradeNode GRADENODE;
		typedef GRADENODE *GRADENODEPTR;

•	Create a pointer to the start of the linked-list called startPtr. The list is empty initially.
•	Create a new node of type GRADENODE that is pointed to by a pointer newPtr of type GRADENODEPTR. Assign the string “Johan” to member lastname and the value 91.5 to member grade (use strcpy). Provide any necessary declarations and statements. 
•	Assume that the list pointed to by startPtr currently consists of 2 nodes – one containing “Johan” and on containing “Samsiah” with member grade 78. The nodes are in alphabetical order. Provide the statements necessary to insert the nodes containing the following data:

“Aarthi”	85.0
“Tan Chong”	73.5
“Priscilla”	66.5

Use pointers previousPtr, currentPtr, and newPtr to perform the insertions. Print out what previousPtr and currentPtr point to before each insertion. Assume that newPtr always points to the new node, and that the new node has already been assigned the data.	
•	Using a loop, printout the data in each node of the list. Use pointer currentPtr to move along the list.
•	Using another loop, delete all the nodes in the list and free the memory associated with each node. Use currentPtr and pointer tempPtr to walk along the list and free memory, respectively.

Make sure that your program is well-documented and proper variable names are used at all times. 

this is my answer but i cant compile it and run

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main()
{
    struct gradeNode
    {
        char lastName[20];
        float grade;
        struct gradeNode *nextPtr;
    };

    typedef struct gradeNode GRADENODE;
    typedef GRADENODE *GRADENODEPTR;


    GRADENODEPTR startPtr=NULL;
    GRADENODEPTR newPtr=NULL;
    GRADENODEPTR previousPtr=NULL;
    GRADENODEPTR currentPtr=NULL;
    GRADENODEPTR tempPtr=NULL;


    /*Node 1*/
    newPtr = malloc(sizeof(GRADENODEPTR*));
    strcpy(newPtr->lastName,"Johan");
    newPtr->grade = 91.5;
    newPtr->nextPtr = NULL;


    startPtr = newPtr;



    /*Node 2*/
    newPtr = malloc(sizeof(GRADENODE));
    strcpy(newPtr->lastName,"Samsiah");
    newPtr->grade = 78;
    startPtr->nextPtr = newPtr;




    /*Node 3*/
    newPtr = malloc(sizeof(GRADENODE));
    strcpy(newPtr->lastName,"Aarthi");
    newPtr->grade = 85.0;


    previousPtr=NULL;
    currentPtr=startPtr;


    newPtr->nextPtr = currentPtr;
    startPtr = newPtr;




    /*Node 4*/
    newPtr = malloc(sizeof(GRADENODE));
    strcpy(newPtr->lastName,"Tan Chong");
    newPtr->grade = 73.5;


    previousPtr = (startPtr->nextPtr)->nextPtr;
    currentPtr=NULL;


    previousPtr->nextPtr = newPtr;
    newPtr->nextPtr = currentPtr;






    /*Node 5*/
    newPtr = malloc(sizeof(GRADENODE));
    strcpy(newPtr->lastName,"Priscilla");
    newPtr->grade = 66.5;


    previousPtr = startPtr->nextPtr;
    currentPtr = (startPtr->nextPtr)->nextPtr;


    previousPtr->nextPtr = newPtr;
    newPtr->nextPtr = currentPtr;




    /*Printing the nodes*/
    currentPtr = startPtr;
    while(currentPtr!=NULL){
        printf("Lastname = %s\nGrade = %.1f\n\n",currentPtr->lastName,currentPtr->grade);
        currentPtr = currentPtr->nextPtr;
    }


    /*Deleting the nodes*/
    currentPtr = startPtr;
    while(currentPtr != NULL){
        tempPtr=currentPtr;
        currentPtr=currentPtr->nextPtr;
        free(tempPtr);
    }

    
    return 0;
}