Before trying to install the Layer Styles, first off make sure you have photoshop closed
1. Firstly unzip your asset pack, select the 30 simple gradient Layer Styles file and copy it.
2. Go to my computer and double click the c:\ drive icon
3. Find the Programs Files folder and double click
4. Find the Adobe folder and double click
5. Find the Photoshop CS2/CS3/CS4/CS5 folder and double click
6. Find the Presets folder and double click
7. Find the Layer Styles folder and double click, now right click and paste or press ctrl+v
8. Now the next time you open photoshop your 30 simple gradient Layer Styles will be available