Right, first of all, have you actually installed FlyaKite? If so, you can right click on your desktop, select "properties", click the Appearance tab and then change the theme in there to Tiger. If you haven't installed FlyaKite, do so now then you should find the skin automatically installed on your system.
Second of all, if you wish to use a downloaded theme, you need to find out what sort of theme it is and hence then knowing how to use it. If the theme has an extension of .wba then it is for WindowsBlinds. If it ends in msstyle then it is a shell theme. Each has its own advantages, if you're using a slower PC, stick to msstyles.
Assuming you use an msstyle, you need to copy the style (make sure you extract if from the zip if it's in one) and put it in the following folder:
C:WINDOWSResourcesThemes
Once there, go back to your desktop and do the steps I outlined at the start of this post and select the theme you just put in the themes folder.
If you still are having difficulty, post your queries here making sure to tell us the problem in plenty of detail, and outline exactly what you have tried.
Hope that helps.

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