JMeter is Java-based application it needs Java Runtime Environment (or better Development Kit - JDK) installed and properly configured.
The easiest way to get it running is following next steps:
1. Download latest JDK from Oracle website (if your system allows - use 64-bit one)
2. Install it somewhere (it's better of location doesn't contain spaces or native characters, something like c:\java would be great)
3. Same for JMeter. Download latest JMeter bundle and unzip it somewhere, i.e. c:\jmeter
4. Open Windows Command Prompt
5. Type following:
SET JAVA_HOME=c:\java
SET PATH=%JAVA_HOME%\bin;%PATH%
cd c:\jmeter\bin
jmeter.bat
Explanation:
1. set environment variable called JAVA_HOME with value of c:\java
2. add \bin folder of Java to your system path
3. navigate to jmeter folder
4. launch jmeter
More on the topic in
JMeter Getting Started Guide