Traditional model of computing with wireless sensors imposes restrictions on how efficiently wireless sensors can be used due to resource constraints. Newer models for interacting with wireless sensors such as Internet of Things and Sensor Cloud aim to overcome these restrictions. In this tutorial, I will discuss sensor cloud architectures, which enable different wireless sensor networks, spread in a huge geographical area to connect together and be used by multiple users at the same time on demand basis. I will further discuss how virtual sensors assist in creating a multiuser environment on top of resource constrained physical wireless sensors and can help in supporting multiple applications on-demand basis. I will then present some security issues and provide overview of the solutions to the problems from the literature. In particular, I will discuss energy efficient privacy and data integrity preserving data aggregation algorithm, risk assessment in sensor cloud as well as attribute-based access control for sensor cloud applications. The topics covered will be: 1. Cloud of Sensors - Sensor Cloud Architectures 2. Virtualization in Sensor Cloud 3. Scheduling and QoS in Sensor Cloud 4. Data compression and Secure Aggregation in Sensor Cloud 5. Security, Privacy and Risk Issues in Sensor Cloud