feat: Add Get-Started section.

Signed-off-by: DivyPatel9881 <[email protected]>

Author: divy9881

README.md

@@ -100,6 +100,37 @@ You can also use the online editor (https://casbin.org/editor/) to write your Ca
 
 https://casbin.org/docs/en/tutorials
 
+## Get started
+
+1. New a Casbin enforcer with a model file and a policy file:
+
+    ```c++
+    Enforcer* e = Enforcer :: NewEnforcer("<path to model.conf>", "<path to policy.csv>");
+    ```
+
+Note: you can also initialize an enforcer with policy in DB instead of file, see [Policy-persistence](#policy-persistence) section for details.
+
+2. Add an enforcement hook into your code right before the access happens:
+
+    ```c++
+    string sub = "alice"; // the user that wants to access a resource.
+    string obj = "data1"; // the resource that is going to be accessed.
+    string act = "read"; // the operation that the user performs on the resource.
+
+    if(e->Enforce({ sub, obj, act })) {
+        // permit alice to read data1
+    } else {
+        // deny the request, show an error
+    }
+    ```
+
+3. Besides the static policy file, Casbin also provides API for permission management at run-time. For example, You can get all the roles assigned to a user as below:
+
+    ```c++
+    vector<string> roles( e->GetImplicitRolesForUser(sub) );
+    ```
+
+
 ## Policy management
 
 Casbin provides two sets of APIs to manage permissions: