Most packs come in .zip or .rar format. Use a tool like WinRAR or 7-Zip to extract them to a dedicated "Pivot Assets" folder.
Don't just drop a gun into a hand. Layer effects. For a laser blast: pivot animator effects pack download
Use the "Raise" and "Lower" buttons in Pivot to ensure your effects (like fire) stay behind your character or in front of the background as needed. Pro Tip: Layering and Transparency Most packs come in