View Compilation Error

0_0_35844944_9417.c:4:5: error: unknown type name 'Node'
     Node *left;
     ^
0_0_35844944_9417.c:5:5: error: unknown type name 'Node'
     Node *right;
     ^
0_0_35844944_9417.c:11:15: error: unknown type name 'Node'
 void preorder(Node *T){
               ^
0_0_35844944_9417.c:16:1: error: unknown type name 'Node'
 Node *create(){
 ^
0_0_35844944_9417.c:20:1: error: unknown type name 'Node'
 Node *insert(Node *T,char x){
 ^
0_0_35844944_9417.c:20:14: error: unknown type name 'Node'
 Node *insert(Node *T,char x){
              ^
0_0_35844944_9417.c: In function 'main':
0_0_35844944_9417.c:37:9: error: unknown type name 'Node'
         Node*T=NULL;
         ^
0_0_35844944_9417.c:47:13: error: unknown type name 'Node'
             Node*T=NULL;
             ^