It’s hard to answer this without more information but hopefully we can point you in the right direction. There are a number of tutorials on the site that cover getting JMeter set up for doing load testing:

• How To Use Apache JMeter To Perform Load Testing on a Web Server
• How To Use JMeter To Record Test Scenarios

If you find that JMeter is not behaving the same as a real user, there are a number of settings you can configure in order to better simulate a real user using a real browser. For instance, a visit via a browser would trigger all resources (e.g. images, css, etc) to be downloaded. That may not be the case with JMeter by default. You can edit the HTTP Request Defaults to retrieve all embedded resources from HTML files. You might also want to look into the HTTP Cookie Manager settings.