Step 1: Open A New Photoshop Document
Open a new document in Photoshop by going up to the File menu and choosing New…, or by using the keyboard shortcut, Ctrl+N. You can choose your own width and height for your document, but if you want to follow along, I chose the 640×480 size from the list of available presets to keep things simple. I’ve also left my Resolution value set to its default of 72 pixels/inch. Since I’m creating this text effect for the web, it makes no difference what I set the resolution value to, so the default value is fine:

Step 2: Add Your Text
With your new blank document open, grab the Type tool from the Tools palette or by pressing T on your keyboard. Make sure black is selected as your foreground color. If it isn’t, just press D on your keyboard to reset it to black. Choose your font in the Options Bar at the top of the screen. Thick, heavy fonts work best for this effect. Then, go ahead and enter your text. I’m going to use “Impact”, and I’ll type the words “LIGHT BURST

Step 3: Resize Your Text With Free Transform
With your text layer selected in the Layers palette, use the keyboard shortcut Ctrl+T to bring up the Free Transform box and handles around your text. Hold down Shift+Alt and drag out any of the corner handles to make your text larger and fill up more of the document area. Holding Shift constrains the text proportions, and holding Alt/Option resizes the text from the center: