how to simulate 1000 concurrent user using jmeter

I could have written it as comment, but it went out of characters.

definitions given by @Quality-Expert are correct but his understanding of your test setup is wrong.

10 loop count doesnt mean 1000*10

It means at a given moment only 1000 concurrent users will be present but they will perform same action 10 times. It doesn't mean 10000 users.

Rampup is 10 doesnt mean 1000 users for 10 seconds

It means 100 users will come online in 1 second and next 100 users will online in next second i.e. in 2 seconds 200 users will come online and this is how 1000 users will come online in 10 seconds.

If you dont provide any test duration test will end their itself, it wont continue after threads have finished their task. If you want to load test with 1000 users then provide some test duration i.e. 10 mintues. Thus test will run with 1000 concurrent users for 10 min. Rampup is just warm up time for system under load test so that it wont face sudden load of 1000 users.

About 10000 load, use need to use distributed set of machines/client of Jmeter which will generate that load or use cloud load testing tools.

Number of Threads- The maximum number of users you want to run.

Ramp-Up Period - Defines how long it takes for JMeter to ramp up from zero users to X number of threads. It is in terms of seconds.

Loop Count - Defines how many times you want each user to run your script.

Other thing is that No. of user depends on your machine CPU , RAM , Physical memory. As far as I know using normal system you can user 250-500 max. users.

If you want to do testing like 1k,10k users then you will have to use cloud systems like Neoload.

As per your given example , you are right about if you put thread user = 1000 & ramp up = 10 then it will run test till 10 seconds for 1000 users.

Let me know if you have still any confusion.