Change Eclipse Theme

Restart eclipse.Then you can change theme:
Open Eclipse Menu -> Window -> Preference -> General -> Appearance

You can change background color:
Open Eclipse Menu -> Window -> Preference -> General -> Appearance -> Color Theme

Cannot change version of project facet Dynamic Web Module to 2.5

PROBLEM:

SOLVE:
Open navigator:

Open "org.eclipse.wst.common.project.facet.core.xml".
Change " <installed facet="jst.web" version="3.0"/>" 
to <installed facet="jst.web" version="2.5"/> and save.

<?xml version="1.0" encoding="UTF-8"?> <faceted-project>   <fixed facet="wst.jsdt.web"/>   <fixed facet="java"/>   <fixed facet="jst.web"/>   <installed facet="java" version="1.6"/>   <installed facet="wst.jsdt.web" version="1.0"/>   <installed facet="jst.web" version="2.5"/> </faceted-project>

Where Eclipse workspace projects is stored?

Your projects are stored in the following directory:

Windows:

<workspace>\.metadata\.plugins\org.eclipse.core.resources\.projects\

Linux / osx:

<workspace>/.metadata/.plugins/org.eclipse.core.resources/.projects/