The easiest way to make sound effects is to use fonts. Many specialty fonts exist that are perfect for creating the feeling of explosions, cracking, gunfire, and more.
Some great resources for these types of fonts are www.blambot.com and www.1001freefonts.com, but be sure to check the terms of use for any free font that you download! Some free font creators do not allow their fonts to be used in commercial projects, so if you're making a comic to sell, you need to be certain you are not breaking any copyright laws!
After downloading a new font and installing it on your computer, you may need to shut down Clip Studio Paint and restart the program in order to get the font to appear in the font list in the Text tool. Once it appears in the Font list, you can use the instructions in Chapter 9, Using Text and Balloon Tools, to lay out your basic...