Here is an easy way to make the light sources in your scene glow.
Clear the scene (select Scene->Clear from the main menu).
Make sure that the Scene and Object properties windows are visible(select Window from the main menu).
Load the pak file from Half-Life.
Add a point light (select Scene->Lights->Add from the main menu and select point).
In the Scene Properties Window click on the Pak Files tab and select the Half-Life pak file. Click on Sprites and select blueflare1 then click the View Sprite button.
Split the view into 4 (select View->Four Viewports from the main menu
Center the sprite around the light in all three 2D viewports.
Select the light (click on it!) and in the Object Properties window un-check Show.
Now add other objects to your scene.
Note that if you move the light, you will have move the sprite as well.