When you want to scan the network hosts within a specific IP range, you have to select Scan IP Range option as shown below:
Figure 1: Scan IP Range
Click Next and enter the end IP address of your IP range. Typically the start IP address of your network is automatically picked up by the application. You can change it as well.
Figure 2: Specify IP Range
When you click Next, the scanning process starts as shown below:
Figure 3: Network Scanning in Progress
Once the scanning is done and you click the Finish button, you see the discovered hosts list as shown below:
Figure 4: Added Hosts List