Let us say we have 5 users in a thread which and we have a situation in which each user or thread is going to hit a different webpage.

For that we use a pre processor called user parameter.

We add a new variable in it and name it url and give it a value.

Then we keep clicking Add user button and keep adding values for various users.

Then in the sampler http request we can simply type ${url} in the server and when we run the thread group for each user a different site will be hit.