updated time

Author: Tomas Baca

docs/10-prerequisities/25-ros2/50-ros1-ros2-patterns/cpp_working_with_time.md

@@ -10,15 +10,31 @@ description: Working with ROS Time in ROS2
 
 ## Comparing times
 
-## Rate
+## rclcpp::Rate
 
-## Duration
+## rclcpp::Duration
 
 Duration object storing an interal of `1 second`:
 ```cpp
 rclcpp::Duration(std::chrono::duration<double>(1.0))
 ```
 
+## rclcpp::Time
+
+* creating the Time object out of a floating point time:
+```cpp
+rclcpp::Duration(std::chrono::duration<double>(1.0))
+```
+
 ## Sleeping
 
+What was in ROS1 done as:
+```cpp
+ros::Duration(duration).sleep();
+```
+is in ROS2 done as:
+```cpp
+clock_->sleep_for(std::chrono::duration<double>(duration));
+```
+
 ## Simulation time