step 1: introduce DReddit Smart Contract and createPost() method

contracts/DReddit.sol

@@ -0,0 +1,22 @@
+pragma solidity ^0.5.0;
+
+contract DReddit {
+
+  struct Post {
+    uint creationDate;   
+    bytes description;   
+    address owner;
+  }
+
+  Post [] public posts;
+
+  function createPost(bytes memory _description) public {
+    uint postId = posts.length++;
+    posts[postId] = Post({
+      creationDate: block.timestamp,
+      description: _description,
+      owner: msg.sender
+    });
+  }
+}
+